vexpress: add gfx init

Change-Id: I0eff29b74d7df331dcbf2c25799eaae4911e54fc
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: https://review.coreboot.org/13749
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
2 files changed