irqchip: gic: Add incorrectly removed raw_spin_lock

Patch 76558811 removed
the raw_spin_lock in gic_show_resume_irq.
This patch adds that back as it is required.

Change-Id: Ia15d6704f3c7b3a646114b595f4bfdc185063f29
CRs-Fixed: 569370
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>