clk: sunxi-ng: h616: Reparent GPU clock during frequency changes

clk: sunxi-ng: h616: Reparent GPU clock during frequency changes

The H616 manual does not state that the GPU PLL supports
dynamic frequency configuration, so we must take extra care when changing
the frequency. Currently any attempt to do device DVFS on the GPU lead
to panfrost various ooops, and GPU hangs.

The manual describes the algorithm for changing the PLL
frequency, which the CPU PLL notifier code already support, so we reuse
that to reparent the GPU clock to GPU1 clock during frequency
changes.

Signed-off-by: Philippe Simons <simons.philippe@gmail.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://patch.msgid.link/20250220113808.1122414-2-simons.philippe@gmail.com
Signed-off-by: Chen-Yu Tsai <wens@csie.org>