ARM: samsung: convert to MULTI_IRQ_HANDLER

Now that there is a generic IRQ handler for multiple VIC devices use it
for samsung to help building multi platform kernels.

Cc: Kukjin Kim <kgene.kim@samsung.com>
Tested-by: Thomas Abraham <thomas.abraham@linaro.org>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>