crash_dump: fix boolreturn.cocci warning

crash_dump: fix boolreturn.cocci warning

./include/linux/crash_dump.h: 119: 50-51: WARNING: return of 0/1 in
function 'is_kdump_kernel' with return type bool

Return statements in functions returning bool should use true/false
instead of 1/0.

Link: https://lkml.kernel.org/r/20211020083905.1037952-1-deng.changcheng@zte.com.cn
Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>
Reported-by: Zeal Robot <zealci@zte.com.cn>
Reviewed-by: Simon Horman <horms@kernel.org>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Ye Guojin <ye.guojin@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>