mmc: card: read the firmware version from ext_csd

Read the firmware version from ext_csd register and print it
for debugging purpose.

Change-Id: Id6b845fc56fdee1cc2674d8ffd45cead946ca216
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Signed-off-by: Ram Prakash Gupta <rampraka@codeaurora.org>