mhi: dev: uci: Handle TIOCMSET ioctl properly

TIOCMSET ioctl is updating the tiocm bits for mhi device.
When TIOCMGET ioctl is issued it returns the tiocm bits
for uci device which is not getting updated as part of
TIOCMSET ioctl. Fix this issue issue by copying the tiocm
bits from mhi dev which gets updated after ul xfer callback.
Also retain the copy of tiocm in uci dev.

Change-Id: I5c1dd1868b31763c1e7afc4c092cc0c5edc610b8
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>