ARM: sunxi: fix gpio drive mask

According to A10 user manual, the width of the drive configuration
for each pin is only 2 bits. Fix the mask so we don't touch values
for other pins.

Signed-off-by: Ma Haijun <mahaijuns@gmail.com>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
ARM: sunxi: Add gmac clock macros

Add macros for gmac clock control, instead of using raw values.
Also add comment noting GMAC ahb gate is in second gate register,
to avoid confusion over same offset as EMAC.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
ARM: sunxi: Move GMAC init code into separate glue layer driver

GMAC init code now exists in a glue layer driver under drivers/net,
instead of sunxi board initialization code. It has been cleaned up
to use macros for clock controls.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>