ARM: gic: Add flag to select 8625 QGIC2 back to back read/write workaround

MSM8625 v1.0 needs the s/w workaround for hready pin access problem
in QGIC2. The workaround is add the lock around every QGIC2 register's
read and write operation to avoid reading the incorrect value from the
QGIC2 registers when back to back read happens on another CPU.

Change-Id: If980c03d2c57b0b9c560b5a746db0535584841d9
Signed-off-by: Trilok Soni <tsoni@codeaurora.org>