shell: Convert to using iterable sections

Convert handling of shell_root_cmds, shell_subcmds, and
shell_dynamic_subcmds to use iterable section macros.

Signed-off-by: Kumar Gala <kumar.gala@intel.com>
diff --git a/cmake/linker_script/common/common-rom.cmake b/cmake/linker_script/common/common-rom.cmake
index 2e260c4..1346853 100644
--- a/cmake/linker_script/common/common-rom.cmake
+++ b/cmake/linker_script/common/common-rom.cmake
@@ -173,6 +173,12 @@
 
 zephyr_iterable_section(NAME shell KVMA RAM_REGION GROUP RODATA_REGION SUBALIGN 4)
 
+zephyr_iterable_section(NAME shell_root_cmds KVMA RAM_REGION GROUP RODATA_REGION SUBALIGN 4)
+
+zephyr_iterable_section(NAME shell_subcmds KVMA RAM_REGION GROUP RODATA_REGION SUBALIGN 4)
+
+zephyr_iterable_section(NAME shell_dynamic_subcmds KVMA RAM_REGION GROUP RODATA_REGION SUBALIGN 4)
+
 zephyr_linker_section(NAME shell_root_cmds KVMA RAM_REGION GROUP RODATA_REGION NOINPUT ${XIP_ALIGN_WITH_INPUT})
 zephyr_linker_section_configure(SECTION shell_root_cmds INPUT ".shell_root_cmd_*" KEEP SORT NAME)