ARM: 7217/1: mmc: mmci: Put power register deviations in variant data

Use variant data to store hardware controller deviations concerning
power registers to improve readability of the code.

Signed-off-by: Sebastian Rasmussen <sebastian.rasmussen@stericsson.com>
Tested-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Ulf Hansson <ulf.hansson@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>