char: msm_smd_pkt: Fix the TIOCMSET IOCTL argument reading

In the TIOCMSET IOCTL call the user passed argument is used
incorrectly to update the SMD channel DTR/CTS signals which
results in unexpected flow control on the SMD channel.

Use the get_user() API to get the user passed value and use the
same value to update SMD channel signals.

CRs-Fixed: 1036867
Change-Id: Ia814892a626b7a291d07ba3670e144f6f09fd41a
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>