omap: Use CONFIG_SMP for test_for_ipi and test_for_ltirq

Otherwise we get the following error when enabling CONFIG_SMP
for omap3_defconfig:

arch/arm/kernel/entry-armv.S: Assembler messages:
arch/arm/kernel/entry-armv.S:48: Error: bad instruction `test_for_ipi r0,r6,r5,lr'
arch/arm/kernel/entry-armv.S:48: Error: bad instruction `test_for_ltirq r0,r6,r5,lr'
arch/arm/kernel/entry-armv.S:48: Error: bad instruction `test_for_ipi r0,r6,r5,lr'
arch/arm/kernel/entry-armv.S:48: Error: bad instruction `test_for_ltirq r0,r6,r5,lr'

Signed-off-by: Tony Lindgren <tony@atomide.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>