ARM: dts: msm: add sdhc2 slot support to msmcobalt

Make necessary changes in DT to enable sdhc2 slot
for msmcobalt and enable sdhc2 for rumi platform.

Change-Id: Idcf1680c44109792c51db617d72949923df95851
Signed-off-by: Talel Shenhar <tatias@codeaurora.org>