[ARM] pxa: don't rely on r2 being preserved over a function call

r2 is not guaranteed to be preserved over a function call, so relying
on it to store the link register over the call to sleep_phys_sp() is
unreliable.  Store the link register on the stack instead.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-pxa/sleep.S

@@ -43,11 +43,11 @@ pxa_cpu_save_cp:
 pxa_cpu_save_sp:
 	@ preserve phys address of stack
 	mov	r0, sp
-	mov	r2, lr
+	str	lr, [sp, #-4]!
 	bl	sleep_phys_sp
 	ldr	r1, =sleep_save_sp
 	str	r0, [r1]
-	mov	pc, r2
+	ldr	pc, [sp], #4
 
 /*
  * pxa27x_cpu_suspend()
@@ -270,5 +270,3 @@ resume_after_mmu:
 	mar	acc0, r2, r3
 #endif
 	ldmfd	sp!, {r4 - r12, pc}		@ return to caller
-
-