clk: versatile: fixup IM-PD1 clock implementation

Register both VCO clocks, give per-logical module unique names
to the clocks so we can have several IM-PD1's connected (in
theory). Implement all the fixed-factor clocks as children of
VCO2.

Tested by using the UARTs and the PL181 MMC block on the IM-PD1,
works flawlessly.

Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>