scripts/checkstack.pl: fix no space expression between sp and offset

When I use older version aarch64 objdump (2.24) to disassemble aarch64
vmlinux, I get the result like below. There is no space between sp and
offset.

ffff800008010000 <dw_apb_ictl_handle_irq>:
ffff800008010000: d503233f hint #0x19
ffff800008010004: a9bc7bfd stp x29, x30, [sp,#-64]!
ffff800008010008: 90011e60 adrp x0, ffff80000a3dc000 <num_ictlrs>
ffff80000801000c: 910003fd mov x29, sp
ffff800008010010: a9025bf5 stp x21, x22, [sp,#32]

When I use newer version aarch64 objdump (2.35), I get
the result like below.
There is a space between sp and offset.

ffff800008010000 <dw_apb_ictl_handle_irq>:
ffff800008010000: d503233f paciasp
ffff800008010004: a9bc7bfd stp x29, x30, [sp, #-64]!
ffff800008010008: 90011e60 adrp x0, ffff80000a3dc000 <num_ictlrs>
ffff80000801000c: 910003fd mov x29, sp
ffff800008010010: a9025bf5 stp x21, x22, [sp, #32]

Add no space support of regular expression for old version objdump.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Kuan-Ying Lee <[e-mail]>
Cc: Casper Li <[e-mail]>
Cc: AngeloGioacchino Del Regno <[e-mail]>
Cc: Chinwen Chang <[e-mail]>
Cc: Matthias Brugger <[e-mail]>
Cc: Qun-Wei Lin <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

scripts/checkstack.pl

···
 	if ($arch =~ '^(aarch|arm)64$') {
 		#ffffffc0006325cc:       a9bb7bfd        stp     x29, x30, [sp, #-80]!
 		#a110:       d11643ff        sub     sp, sp, #0x590
-		$re = qr/^.*stp.*sp, \#-([0-9]{1,8})\]\!/o;
+		$re = qr/^.*stp.*sp, ?\#-([0-9]{1,8})\]\!/o;
 		$dre = qr/^.*sub.*sp, sp, #(0x$x{1,8})/o;
 	} elsif ($arch eq 'arm') {
 		#c0008ffc:	e24dd064	sub	sp, sp, #100	; 0x64