mhi: core: synchronize fast resume and state change event thread

It's possible during fast resume transition device could be sending a state
change event. It's important these two thread processed in a synchronous
order to avoid out of sync issues between host and device.

CRs-Fixed: 24956804
Change-Id: I94724cd70bdc728cb5757422c33a51912dfa3cc7
Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>