WIP: mmc: mmci: add qcom specific program end support

WIP: mmc: mmci: add qcom specific program end support

This patch adds support to programend interrupt which is very specific
to QCOM integration. This interrupt is use as busy signal when a command
forces the card to enter into programming state like CMD6 writing to
ext_csd registers.

This also fixes the __mmc_switch timeout issue reproted with latest
versions of the eMMC used on DB600c board.

This is just a WIP patch, will be cleaned up soon.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>