mmc: sdhci-pxav3: add IRQ wake up support

[cjb: The MMP3 architecture requires a registered interrupt to retire wfi
when waking from suspend.]

Signed-off-by: Jialing Fu <jlfu@marvell.com>
Signed-off-by: Kevin Liu <kliu5@marvell.com>
Signed-off-by: Chris Ball <cjb@laptop.org>