msm: 9625: Add support for SDC2

Add device tree bindings for removable SD
card slot. SDC2 supports SD3.0 spec and hotplug.

Change-Id: Ie54d4aa045817c260a19e81a8b4ce84222f0a68b
Signed-off-by: Oluwafemi Adeyemi <aadeyemi@codeaurora.org>