msm: mhi_dev: Add reset command support

The modem host driver can issue a reset command to
the device on scenarios such as uninstalling the
host driver components on fatal error detection.
The host issues a reset to the device to indicate
the host driver is uninstalling and preparing to
reinitialize the MHI (modem host interface) driver
on the host. The device prepares the channels to
stop sending data and sends completion command to
the host.

Change-Id: Ic0b86e1521247b8d11c2f5d3b9068ca990d99a63
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>