modules: tf-m: generate tfm_merged.bin from tfm_merged.hex

Since `tfm_merged.bin` now contains BL2, it can only be used for the
same purposes as `tfm_merged.hex` (intial firmware loading). Therefore
it should be using the confirmed images that `tfm_merged.hex` does.

Since the only difference between the two files with that change is now
the output format, we can directly generate `tfm_merged.bin` from
`tfm_merged.hex` with `objcopy` instead of going through `mergehex.py`.

Signed-off-by: Jordan Yates <jordan@embeint.com>

Author: JordanYates

modules/trusted-firmware-m/CMakeLists.txt

@@ -618,24 +618,21 @@ if(CONFIG_BUILD_WITH_TFM)
         $<$<BOOL:${CONFIG_TFM_BL1}>:$<TARGET_PROPERTY:tfm,BL2_SIGNED_HEX_FILE>>
         $<$<NOT:$<BOOL:${CONFIG_TFM_BL1}>>:$<TARGET_PROPERTY:tfm,BL2_HEX_FILE>>
         ${S_NS_SIGNED_CONFIRMED_HEX_FILE}
+
+      COMMAND ${CMAKE_OBJCOPY} --input-target=ihex --output-target=binary ${MERGED_HEX_FILE} ${MERGED_BIN_FILE}
     )
 
     set_property(GLOBAL APPEND PROPERTY extra_post_build_commands
       COMMAND ${sign_cmd_s_ns_hex}
 
-      COMMAND ${PYTHON_EXECUTABLE} ${ZEPHYR_BASE}/scripts/build/mergehex.py
-        -o ${MERGED_BIN_FILE} --output-bin
-        $<$<BOOL:${CONFIG_TFM_BL1}>:$<TARGET_PROPERTY:tfm,BL2_SIGNED_HEX_FILE>>
-        $<$<NOT:$<BOOL:${CONFIG_TFM_BL1}>>:$<TARGET_PROPERTY:tfm,BL2_HEX_FILE>>
-        ${S_NS_SIGNED_HEX_FILE}
-
       COMMAND ${CMAKE_OBJCOPY} --input-target=ihex --output-target=binary ${S_NS_SIGNED_HEX_FILE} ${S_NS_SIGNED_BIN_FILE}
     )
 
     set_property(GLOBAL APPEND PROPERTY extra_post_build_byproducts
       ${S_NS_SIGNED_CONFIRMED_HEX_FILE}
       ${S_NS_HEX_FILE}
       ${S_NS_SIGNED_HEX_FILE}
+      ${S_NS_SIGNED_BIN_FILE}
       ${MERGED_HEX_FILE}
       ${MERGED_BIN_FILE}
     )