ARC: [plat-arcfpga] No need for init_irq hack

With all IRQs unmasked by default on all cores, it is no longer needed
to unmask them explicitly.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

diff --cc arch/arc/plat-arcfpga/Makefile
Simple merge

diff --cc arch/arc/plat-arcfpga/include/plat/irq.h
Simple merge

diff --cc arch/arc/plat-arcfpga/irq.c
Simple merge

diff --cc arch/arc/plat-arcfpga/platform.c
Simple merge