ARM: OMAP: don't build hwspinlock in vain

Cleanup: don't build mach-omap2/hwspinlock.c if the OMAP hwspinlock
driver isn't configured.

This will both shorten build time and avoid registering a device
which isn't needed.
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/Makefile

@@ -268,6 +268,8 @@ obj-y					+= $(smc91x-m) $(smc91x-y)
 
 smsc911x-$(CONFIG_SMSC911X)		:= gpmc-smsc911x.o
 obj-y					+= $(smsc911x-m) $(smsc911x-y)
-obj-$(CONFIG_ARCH_OMAP4)		+= hwspinlock.o
+ifneq ($(CONFIG_HWSPINLOCK_OMAP),)
+obj-y					+= hwspinlock.o
+endif
 
 obj-y					+= common-board-devices.o twl-common.o