mmc: sdhci-msm: Add wakeup functionality support for sdio

This adds external GPIO wakeup support to sdhci-msm driver
for sdio cards.

Change-Id: Ic3e280b975d293ea8adadadafecfa8115fe5f428
Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
[xiaonian@codeaurora.org: fixed merge conflicts &
one compilation error]
Signed-off-by: Xiaonian Wang <xiaonian@codeaurora.org>