clk: sunxi: Add VE (Video Engine) module clock driver for sun[457]i

The video engine has its own special module clock, consisting of a clock
gate, configurable dividers, and a reset control.

On later (sun[68]i) families, the reset control is moved out of this
piece of hardware and grouped with reset controls of other peripherals.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Tested-by: Jens Kuske <jenskuske@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>