x86/kaslr: Fix process_mem_region()'s return value

Fix the following coccicheck warning:

  ./arch/x86/boot/compressed/kaslr.c:670:8-9: WARNING: return of 0/1 in
  function 'process_mem_region' with return type bool.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220421202556.129799-1-jiapeng.chong@linux.alibaba.com