sunxi: display: Add a few extra register and constant defines

Add a few extra sunxi display registers and constant defines.

Also rename some existing defines (e.g. dropping _GCTRL) and make
some more generic (e.g. dropping the 2x scaling from
SUNXI_LCDC_TCON1_TIMING_V_TOTAL).

This is a preparation patch for adding composite video out support.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>