ANDROID: Fix a build warning inside early_memblock_nomap

Fix a warning caused by ignoring the return value of kstrtobool:

 mm/memblock.c: In function 'early_memblock_nomap':
>> mm/memblock.c:1910:9: warning: ignoring return value of 'kstrtobool' declared with attribute 'warn_unused_result' [-Wunused-result]
    1910 |         kstrtobool(str, &memblock_nomap_remove);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fixes: 3c2f107a ("ANDROID: mm: memblock: avoid to create memmap for memblock nomap regions")
Bug: 227974747
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I9cc1145492e47a6604b8204165058d8617c0aaaa