microblaze/mm: put mm_cmdline_setup() in .init.text section

As reported by lkp, there is a section mismatch of mm_cmdline_setup() and
memblock.  The reason is we don't specify the section of
mm_cmdline_setup() and gcc put it into .text.unlikely.

As mm_cmdline_setup() is only used in mmu_init(), which is in .init.text
section, put mm_cmdline_setup() into it too.

Link: https://lkml.kernel.org/r/20250328010136.13139-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202503241259.kJV3U7Xj-lkp@intel.com/
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: RichardWeiYang

arch/microblaze/mm/init.c

@@ -118,7 +118,7 @@ int page_is_ram(unsigned long pfn)
 /*
  * Check for command-line options that affect what MMU_init will do.
  */
-static void mm_cmdline_setup(void)
+static void __init mm_cmdline_setup(void)
 {
 	unsigned long maxmem = 0;
 	char *p = cmd_line;