ARM: dts: add SDC2 and SDC4 to the MSM8660 family

To make the picture complete, add DTS entries also for the
second and fourth MMC/SD blocks on the MSM8660. SDC2 is
an 8-bit interface and SDC4 is a 4-bit interface.

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>