arm/dt: msmcopper-sim: Add support for SDC2 slot

In the new simulator release, the SD card slot is
changed to SDC2. Hence, enable SDC2 slot and
disable SDC3 slot which will be no longer used.
The CMD23 is supported as well in the new release,
hence remove the "disable_cmd23" property.

Also, since SDC3 and SDC4 slots are never used in sim or
rumi versions, disable them in SoC file and let them be
enabled in the board specific .dts file if any future
board supports it.

Change-Id: Id507356af76b1ee64d3d1c6d12d276ed3db806fd
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>