sunxi-video: check there is enough memory

Check there is enough memory for an EDID discovered mode, and if not don't
use it. This avoids crashing with a kernel panic when we encounter modes
for which we don't have enough reserved fbmem.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
sunxi-video: Fix double pll modes not working properly on sun5i and sun7i

Signed-off-by: Hans de Goede <hdegoede@redhat.com>