mmc: tmio: fix .set_ios(MMC_POWER_UP) handling

The aggressive clock gating for TMIO MMC patch has broken switching
interface power on, using MFD or platform callbacks. Restore the
ios->power_mode == MMC_POWER_UP && ios->clock == 0 case handling.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Chris Ball <cjb@laptop.org>