ARM: configs: aspeed_g5: Reneable DRM_FBDEV_EMULATION

DRM_FBDEV_EMULATION previously selected FB and was default y as long as DRM
was enabled. In commit f611b1e7 ("drm: Avoid circular dependencies for
CONFIG_FB") the select was replaced with a depends on FB, disabling
DRM_FBDEV_EMULATION for configurations that had it enabled.

Fixes: f611b1e7 ("drm: Avoid circular dependencies for CONFIG_FB")
Signed-off-by: Joel Stanley <joel@jms.id.au>