clk: sunxi-ng: a523: add USB mod clocks

Add the clocks driving the USB subsystem: this just covers the two
clocks creating the 12 MHz rate for the OHCI (USB 1.x) device. The rest
of the USB clocks are either gate clocks (added later) or created
internal to the USB IP.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://patch.msgid.link/20250307002628.10684-11-andre.przywara@arm.com


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