drivers/gpu/drm: disable drm fbdev emulation

DRM FBDev emulation allocates dynamic hw resources on first open
of the DRM driver, leading to a reduced hw resources for the
first real client. It also does not properly handle virtual
displays like the writeback connector, and is incompatible with
the continuous splash feature. Need to enable FB support with
basic DRM to be compatible with varius other drivers.

Change-Id: I00b8be6f01cf2536dde4039f7e2944c211f428d8
Signed-off-by: Lloyd Atkinson <latkinso@codeaurora.org>