clk: sunxi-ng: sun6i-a31: Enable PLL-MIPI LDOs when ungating it

The PLL-MIPI clock is somewhat special as it has its own LDOs which
need to be turned on for this PLL to actually work and output a clock
signal.

Add the 2 LDO enable bits to the gate bits. This fixes issues with
the TCON not sending vblank interrupts when the tcon and dot clock are
indirectly clocked from the PLL-MIPI clock.

Fixes: c6e6c96d ("clk: sunxi-ng: Add A31/A31s clocks")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>