drm/tegra: Remove local fbdev emulation Kconfig option

DRM_TEGRA_FBDEV config is currently used to enable/disable legacy fbdev
emulation for the tegra kms driver.

Remove this local config option and use the top level DRM_FBDEV_EMULATION
config option instead.

Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1445933459-5249-4-git-send-email-architt@codeaurora.org


Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>