[nrf fromlist] modules: hal_nordic: nrfx: Add support for custom NRFX_DIR on Sysbuild

Add support for custom NRFX_DIR for Sysbuild builds by checking if
NRFX_DIR has been defined in Sysbuild.

Upstream PR #: 93583

Signed-off-by: Michał Bainczyk <[email protected]>

Author: mib1-nordic

modules/hal_nordic/nrfx/CMakeLists.txt

@@ -5,6 +5,8 @@ zephyr_library()
 
 # The nrfx source directory can be override through the definition of the NRFX_DIR symbol
 # during the invocation of the build system
+zephyr_get(NRFX_DIR SYSBUILD GLOBAL)
+
 if(NOT DEFINED NRFX_DIR)
   set(NRFX_DIR ${ZEPHYR_CURRENT_MODULE_DIR}/nrfx CACHE PATH "nrfx Directory")
 endif()