sunxi: video: Give hotplug-detect (hpd) signal some time to show up

When using a hdmi powered hdmi to vga dongle, and cold booting a sunxi
device, the hpd detect code would not see the dongle (until a warm reboot),
because the dongle needs some time to boot.

Testing has shown that this dongle needs 213ms to respond on a cold boot,
so wait up to 300ms for a hpd signal to show up before giving up.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
sunxi: video: Set input sync enable

Add a write to the "unknown" (*) register to enable auto input sync, when
initially adding sunxi hdmi output support this magic write from the android
kernel code was missed, causing lcdc -> hdmi encoder sync problems.

With this write added, we can drop the modesetting retries and the extra
delays added to work around these sync problems.

*) "unknown" is the actual name of this register in the android kernel sources

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