x86/kaslr: Return boolean values from a function returning bool

Fix the following coccicheck warnings:

  ./arch/x86/boot/compressed/kaslr.c:642:10-11: 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://lkml.kernel.org/r/1615283963-67277-1-git-send-email-jiapeng.chong@linux.alibaba.com