Relocate module Kconfig into mcuboot/zephyr/

Relocate module-level Kconfig declarations into the module's
zephyr/ subdirectory so that it is visible for external build
configurations.  Removed sourcing of Kconfig.zephyr

Restore sourcing of Kconfig.zephyr to stripped boot/zephyr/Kconfig.

Building with `west build -p always -b nrf52840dk_nrf52840
mcuboot/boot/zephyr` succeeds.

Building with `west build -p always -b nrf52840dk_nrf52840
mcuboot/samples/zephyr_external_config` fails with:

[48/256] Building C object modules/mbedtls/CMakeFiles/modules__mbedtls.dir/home/zephyr/mcuboot_dev/modules/crypto/mbedtls/library/ecjpake.c.obj
FAILED: modules/mbedtls/CMakeFiles/modules__mbedtls.dir/home/zephyr/mcuboot_dev/modules/crypto/mbedtls/library/ecjpake.c.obj
ccache /home/zephyr/zephyr-sdk-0.15.0/arm-zephyr-eabi/bin/arm-zephyr-eabi-gcc -DKERNEL -DMBEDTLS_CONFIG_FILE=\"mcuboot-mbedtls-cfg.h\" -DNRF52840_XXAA -D_FORTIFY_SOURCE=2 -D__PROGRAM_START -D__ZEPHYR__=1 -I/home/zephyr/mcuboot_dev/zephyr/include -I/home/zephyr/mcuboot_dev/build/zephyr/include/generated -I/home/zephyr/mcuboot_dev/zephyr/soc/arm/nordic_nrf/nrf52 -I/home/zephyr/mcuboot_dev/zephyr/soc/arm/nordic_nrf/common/. -I/home/zephyr/mcuboot_dev/modules/hal/cmsis/CMSIS/Core/Include -I/home/zephyr/mcuboot_dev/modules/hal/nordic/nrfx -I/home/zephyr/mcuboot_dev/modules/hal/nordic/nrfx/drivers/include -I/home/zephyr/mcuboot_dev/modules/hal/nordic/nrfx/mdk -I/home/zephyr/mcuboot_dev/zephyr/modules/hal_nordic/nrfx/. -I/home/zephyr/mcuboot_dev/zephyr/modules/hal_nxp/. -I/home/zephyr/mcuboot_dev/modules/debug/segger/SEGGER -I/home/zephyr/mcuboot_dev/modules/debug/segger/Config -I/home/zephyr/mcuboot_dev/zephyr/modules/segger/. -I/home/zephyr/mcuboot_dev/modules/crypto/mbedtls/include -I/home/zephyr/mcuboot_dev/modules/crypto/mbedtls/library -I/home/zephyr/mcuboot_dev/zephyr/modules/mbedtls/configs -I/home/zephyr/mcuboot_dev/zephyr/modules/mbedtls/include -isystem /home/zephyr/mcuboot_dev/zephyr/lib/libc/minimal/include -isystem /home/zephyr/zephyr-sdk-0.15.0/arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/12.1.0/include -isystem /home/zephyr/zephyr-sdk-0.15.0/arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/12.1.0/include-fixed -fno-strict-aliasing -Og -imacros /home/zephyr/mcuboot_dev/build/zephyr/include/generated/autoconf.h -ffreestanding -fno-common -g -gdwarf-4 -fdiagnostics-color=always -mcpu=cortex-m4 -mthumb -mabi=aapcs -mfp16-format=ieee --sysroot=/home/zephyr/zephyr-sdk-0.15.0/arm-zephyr-eabi/arm-zephyr-eabi -imacros /home/zephyr/mcuboot_dev/zephyr/include/zephyr/toolchain/zephyr_stdint.h -Wall -Wformat -Wformat-security -Wno-format-zero-length -Wno-main -Wno-pointer-sign -Wpointer-arith -Wexpansion-to-defined -Wno-unused-but-set-variable -Werror=implicit-int -fno-pic -fno-pie -fno-asynchronous-unwind-tables -fno-reorder-functions --param=min-pagesize=0 -fno-defer-pop -fmacro-prefix-map=/home/zephyr/mcuboot_dev/mcuboot/samples/zephyr_external_config=CMAKE_SOURCE_DIR -fmacro-prefix-map=/home/zephyr/mcuboot_dev/zephyr=ZEPHYR_BASE -fmacro-prefix-map=/home/zephyr/mcuboot_dev=WEST_TOPDIR -ffunction-sections -fdata-sections -std=c99 -nostdinc -MD -MT modules/mbedtls/CMakeFiles/modules__mbedtls.dir/home/zephyr/mcuboot_dev/modules/crypto/mbedtls/library/ecjpake.c.obj -MF modules/mbedtls/CMakeFiles/modules__mbedtls.dir/home/zephyr/mcuboot_dev/modules/crypto/mbedtls/library/ecjpake.c.obj.d -o modules/mbedtls/CMakeFiles/modules__mbedtls.dir/home/zephyr/mcuboot_dev/modules/crypto/mbedtls/library/ecjpake.c.obj -c /home/zephyr/mcuboot_dev/modules/crypto/mbedtls/library/ecjpake.c
<command-line>: fatal error: mcuboot-mbedtls-cfg.h: No such file or directory

Signed-off-by: Gregory SHUE <[email protected]>

Author: legrand-gregshue