mmc: tmio: remove work-around for unmasked SDIO interrupts

SDIO IRQs got unmasked on sh-mobile while writing to the
CTL_CLK_AND_WAIT_CTL register, because that register at address 0x138
is not implemented on those SoCs and writes to it overwrite the
register at address 0x38: CTL_SDIO_IRQ_MASK. Previous patches
eliminated access to register above 0xff on sh-mobile, so that this
work-around isn't needed anymore.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Chris Ball <cjb@laptop.org>