mmc: jz4740: Reset the device requesting the interrupt

In case a bootloader leaves the device in a bad state,
requesting the interrupt before resetting results in a bad
interrupt loop.

Signed-off-by: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
[Ezequiel: cleanup commit description]
Tested-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.co.uk>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>