ARM: imx: build CPU suspend code only when needed

The ARM CPU suspend function has its own configuration symbol,
which we need to use for conditionalizing any code calling into
it as well.

arch/arm/mach-imx/built-in.o: In function `v7_cpu_resume':
/git/arm-soc/arch/arm/mach-imx/headsmp.S:57: undefined
 reference to `cpu_resume'

Cc: Sascha Hauer <kernel@pengutronix.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/mach-imx/headsmp.S

@@ -24,7 +24,7 @@ ENTRY(v7_secondary_startup)
 ENDPROC(v7_secondary_startup)
 #endif
 
-#ifdef CONFIG_PM
+#ifdef CONFIG_ARM_CPU_SUSPEND
 /*
  * The following code is located into the .data section.  This is to
  * allow phys_l2x0_saved_regs to be accessed with a relative load