board: storage: enable SDIO wakeup from msm pin

If SDIO slot is using the dedicated MSM pins rather than GPIO
pins then SDIO wakeup interrupt configuration would require
calling msm_mpm_* APIs. For such slots, let's indicate this
by setting a "mpm_sdiowakeup_int" platform entry to appropriate
MPM interrupt number. SDCC will use this entry to call
msm_mpm_* APIs when required.

Change-Id: I8fbeb9bd54c68f0285427d5754444818b66e6e4f
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>