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/csumpartialcopyuser.S

@@ -68,7 +68,7 @@
  * so properly, we would have to add in whatever registers were loaded before
  * the fault, which, with the current asm above is not predictable.
  */
-		.section .fixup,"ax"
+		.pushsection .fixup,"ax"
 		.align	4
 9001:		mov	r4, #-EFAULT
 		ldr	r5, [fp, #4]		@ *err_ptr
@@ -80,4 +80,4 @@
 		strneb	r0, [r1], #1
 		bne	9002b
 		load_regs
-		.previous
+		.popsection