[nrf fromtree]platform: nordic_nrf: Split the target_cfg for different platforms

This splits the target_cfg.c file for the different platfoms.
It splits the file into two files one for the nRF54L and one for
the nRF91/nRF53 series.

There is no need for the peripherals to be in the same file as
the configuration code. There is already a header which
provides extern definitions for all the peripherals a
device supports which can be used for for source files
needing to configure peripherals. So this peripheral definitions
are placed in a separate file.

Most of the code is taken unchanged from the target_cfg.c file
and the uneeded ifdefs got removed.

The init_debug function got rewritten without changing the logic
of it.

Signed-off-by: Georgios Vasilakis <georgios.vasilakis@nordicsemi.no>
Change-Id: I19071727061b8952e3abbae20dd182c822234427
(cherry picked from commit 37e8dc4)

Author: Vge0rge

platform/ext/target/nordic_nrf/common/core/CMakeLists.txt

@@ -206,6 +206,9 @@ target_sources(tfm_spm
         tfm_hal_platform_common.c
         faults.c
         target_cfg.c
+        $<$<BOOL:${HAS_RRAMC}>:${CMAKE_CURRENT_SOURCE_DIR}/target_cfg_54l.c>
+        $<$<BOOL:${HAS_NVMC}>:${CMAKE_CURRENT_SOURCE_DIR}/target_cfg_53_91.c>
+        secure_peripherals_defs.c
 )
 
 target_sources(tfm_s