checkstack.pl: fix for aarch64

There is actually a space after "sp," like this,

    ffff2000080813c8:       a9bb7bfd        stp     x29, x30, [sp, #-80]!

Right now, checkstack.pl isn't able to print anything on aarch64,
because it won't be able to match the stating objdump line of a function
due to this missing space.  Hence, it displays every stack as zero-size.

After this patch, checkpatch.pl is able to match the start of a
function's objdump, and is then able to calculate each function's stack
correctly.

Link: http://lkml.kernel.org/r/20181207195843.38528-1-cai@lca.pw
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: Qian Cai

scripts/checkstack.pl

@@ -47,8 +47,8 @@
 	$xs	= "[0-9a-f ]";	# hex character or space
 	$funcre = qr/^$x* <(.*)>:$/;
 	if ($arch eq 'aarch64') {
-		#ffffffc0006325cc:       a9bb7bfd        stp     x29, x30, [sp,#-80]!
-		$re = qr/^.*stp.*sp,\#-([0-9]{1,8})\]\!/o;
+		#ffffffc0006325cc:       a9bb7bfd        stp     x29, x30, [sp, #-80]!
+		$re = qr/^.*stp.*sp, \#-([0-9]{1,8})\]\!/o;
 	} elsif ($arch eq 'arm') {
 		#c0008ffc:	e24dd064	sub	sp, sp, #100	; 0x64
 		$re = qr/.*sub.*sp, sp, #(([0-9]{2}|[3-9])[0-9]{2})/o;