msm: smp2p_gpio_test: Correct interrupt header include

smp2p_gpio_test includes <linux/irq.h> but only as a way to access
<linux/interrupt.h>.

Correctly include interrupt.h instead of irq.h.

Change-Id: I26aee606ce154ee0deaff881a538dc4fa206f3d0
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>