plat/arm/rdn2: update gic redistributor base address
plat/arm/rdn2: update gic redistributor base address

RD-N2 platform has been updated to use six GIC ITS blocks. This results
in change in base address of the GIC Redistributor to accomodate two
new GIC ITS blocks. Update the base address of GICR to reflect the same.

Signed-off-by: Vijayenthiran Subramaniam <762698363137248267721733483077a93dddd540@arm.com>
Change-Id: I740a547328fb9a9f25d7a09c08e61bdbc8bf781c

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware