[nrf fromtree] tests: drivers: spi: remove useless files and testcases

- with the updates made to the spi_ll_stm32 driver,
we no longer need to configure the 16-bit frame/word size
in the DTS overlay file. The test_spi_word_size_16 testsuite
helps us verify the 16-bit frame mode supported on
the ST platform.

- remove testcases that use thoses files in testcase.yaml

Signed-off-by: Fabrice DJIATSA <[email protected]>
(cherry picked from commit 746d60b)

Author: djiatsaf-st

tests/drivers/spi/spi_loopback/overlay-stm32-spi-16bits-dma-dt-nocache-mem.conf

@@ -51,17 +51,6 @@ tests:
       - robokit1
     integration_platforms:
       - sam_e70_xplained/same70q21
-  drivers.spi.stm32_spi_16bits_frames.loopback:
-    extra_args:
-      - EXTRA_CONF_FILE="overlay-stm32-spi-16bits.conf"
-      - DTC_OVERLAY_FILE="overlay-stm32-spi-16bits.overlay"
-    platform_allow:
-      - nucleo_h743zi
-      - nucleo_h753zi
-      - nucleo_h745zi_q/stm32h745xx/m4
-      - nucleo_h745zi_q/stm32h745xx/m7
-    integration_platforms:
-      - nucleo_h743zi
   drivers.spi.stm32_spi_dma.loopback:
     extra_args: EXTRA_CONF_FILE="overlay-stm32-spi-dma.conf"
     platform_allow:
@@ -98,29 +87,6 @@ tests:
       - nucleo_h745zi_q/stm32h745xx/m7
     integration_platforms:
       - nucleo_h743zi
-  drivers.spi.stm32_spi_16bits_frames_dma.loopback:
-    extra_args:
-      - EXTRA_CONF_FILE="overlay-stm32-spi-16bits-dma.conf"
-      - DTC_OVERLAY_FILE="overlay-stm32-spi-16bits.overlay"
-    platform_allow:
-      - nucleo_h743zi
-      - nucleo_h753zi
-      - nucleo_h745zi_q/stm32h745xx/m4
-      - nucleo_h745zi_q/stm32h745xx/m7
-    integration_platforms:
-      - nucleo_h743zi
-  drivers.spi.stm32_spi_16bits_frames_dma_dt_nocache_mem.loopback:
-    extra_args:
-      - EXTRA_CONF_FILE="overlay-stm32-spi-16bits-dma-dt-nocache-mem.conf"
-      - DTC_OVERLAY_FILE="overlay-stm32-spi-16bits.overlay"
-    filter: CONFIG_CPU_HAS_DCACHE
-    platform_allow:
-      - nucleo_h743zi
-      - nucleo_h753zi
-      - nucleo_h745zi_q/stm32h745xx/m4
-      - nucleo_h745zi_q/stm32h745xx/m7
-    integration_platforms:
-      - nucleo_h743zi
   drivers.spi.stm32_spi_interrupt.loopback:
     extra_args: EXTRA_CONF_FILE="overlay-stm32-spi-interrupt.conf"
     platform_allow: