msm: mhi_dev: Send BHI interrupt vector notification

BHI device notification is sent to update host of a
state change. Under certain conditions if the host
does not see the device ready it waits for an interrupt
notification to indicate a state change. The BHI
interrupt vector is utilized to send a MSI during this
event prior to M0 state.

As part of the waiting for the MHI state transition
update using msleep and wait enough time to allow
host to set the M0 state transition after sending
the MSI.

Change-Id: I256960cbb874c1dade2e710b644da5e76f584ef2
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>