mmc: card: Increase sanitize command timeout

The current timeout value is 30 sec and with this busy timeouts
are observed on few eMMC cards. Hence, increase it to 240 sec
which is already being used in IOCTL variant of sanitize command.
It helped resolve such busy timeout issues.

Change-Id: I08993ac9fb02520267b58bddee51f9c166f129ff
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>