clk: impd1: add pclk clocks

The IM-PD1 PrimeCells all have pclk assignments though this clock
cannot be controlled, and we need to provide this as a dummy
clock for the PL061 GPIO driver to probe, so let's assign it to
all the cells on the board.

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