arm64: defconfig: Switch to PL11x DRM driver

This switches out the old fbdev PL11x driver to the new
DRM driver in the Aarch64/ARM64 defconfig. Some ARM
reference designs use this IP with the Silicon Image
SII902x HDMI bridge so activate both.

The required DTS changes are already in-tree.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>