ARM: Make consolidated PM sleep code depend on PM_SLEEP

CONFIG_PM is now set whenever we support either runtime PM in addition
to suspend and hibernate.  This causes build errors when runtime PM is
enabled on a platform, but the CPU does not have the appropriate support
for suspend.

So, switch this code to use CONFIG_PM_SLEEP rather than CONFIG_PM to
allow runtime PM to be enabled without causing build errors.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mm/proc-arm920.S b/arch/arm/mm/proc-arm920.S
index 219980e..394b623 100644
--- a/arch/arm/mm/proc-arm920.S
+++ b/arch/arm/mm/proc-arm920.S
@@ -390,7 +390,7 @@
 /* Suspend/resume support: taken from arch/arm/plat-s3c24xx/sleep.S */
 .globl	cpu_arm920_suspend_size
 .equ	cpu_arm920_suspend_size, 4 * 3
-#ifdef CONFIG_PM
+#ifdef CONFIG_PM_SLEEP
 ENTRY(cpu_arm920_do_suspend)
 	stmfd	sp!, {r4 - r7, lr}
 	mrc	p15, 0, r4, c13, c0, 0	@ PID