plat/rockchip: Use common gicv2.mk

Compiling BL31 for the Rockchip platform now produces a message about
the deprecation of gic_common.c.
Follow the advice and use include gicv2.mk instead.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Change-Id: I396b977d57975dba27cfed801ad5264bbbde2b5e
4 files changed