ARM: fix build error in arch/arm/kernel/process.c

/tmp/ccJ3ssZW.s: Assembler messages:
/tmp/ccJ3ssZW.s:1952: Error: can't resolve `.text' {.text section} - `.LFB1077'

This is caused because:

	.section .data
	.section .text
	.section .text
	.previous

does not return us to the .text section, but the .data section; this
makes use of .previous dangerous if the ordering of previous sections
is not known.

Fix up the other users of .previous; .pushsection and .popsection are
a safer pairing to use than .section and .previous.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/lib/copy_from_user.S

@@ -90,7 +90,7 @@ ENTRY(__copy_from_user)
 
 ENDPROC(__copy_from_user)
 
-	.section .fixup,"ax"
+	.pushsection .fixup,"ax"
 	.align 0
 	copy_abort_preamble
 	ldmfd	sp!, {r1, r2}
@@ -100,5 +100,5 @@ ENDPROC(__copy_from_user)
 	bl	__memzero
 	ldr	r0, [sp], #4
 	copy_abort_end
-	.previous
+	.popsection