[ARM] 5075/1: i2c-pxa: move i2c pin setup and PCFR_PI2CEN handling into arch/arm/mach-pxa

This fixes a build error introduced when the power manager
register definitions were moved into pxa2xx-regs.h.

Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>