ARM: ux500: fix I2C4 clock bit

The PCLK for I2C4 is controlled by bit 10 in the PCKEN registers
while the KCLK is controlled by bit 9 on the KCKEN, it's
one of these odd assymetric things. Correct the PCLK bit to 10.

Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>