ARM: decompressor: move headroom variable out of LC0

Before breaking up LC0 into different pieces, move out the variable
that is already place-relative (given that it subtracts 'restart' in
the expression) and so its value does not need to be added to the
runtime address of the LC0 symbol itself.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>

arch/arm/boot/compressed/head.S

@@ -287,7 +287,7 @@ not_angel:
 		 */
 		mov	r0, pc
 		cmp	r0, r4
-		ldrcc	r0, LC0+28
+		ldrcc	r0, .Lheadroom
 		addcc	r0, r0, pc
 		cmpcc	r4, r0
 		orrcc	r4, r4, #1		@ remember we skipped cache_on
@@ -664,9 +664,11 @@ LC0:		.word	LC0			@ r1
 		.word	_got_start		@ r11
 		.word	_got_end		@ ip
 		.word	.L_user_stack_end	@ sp
-		.word	_end - restart + 16384 + 1024*1024
 		.size	LC0, . - LC0
 
+.Lheadroom:
+		.word	_end - restart + 16384 + 1024*1024
+
 .Linflated_image_size_offset:
 		.long	(input_data_end - 4) - .