efi: fix 32bit kernel boot failed problem using efi

Commit 35d5134b
("x86/efi: Correct EFI boot stub use of code32_start")
imported a bug, which will cause 32bit kernel boot failed
using efi method. It should use the label's address instead
of the value stored in the label to caculate the address of
code32_start.
Signed-off-by: Fupan Li <fupan.li@windriver.com>
Reviewed-by: Matt Fleming <matt.fleming@intel.com>

arch/x86/boot/compressed/head_32.S

@@ -54,7 +54,7 @@ ENTRY(efi_pe_entry)
 	call	reloc
 reloc:
 	popl	%ecx
-	subl	reloc, %ecx
+	subl	$reloc, %ecx
 	movl	%ecx, BP_code32_start(%eax)
 
 	sub	$0x4, %esp