mhi: core: fix fast forward recycling of event rings

Some low priority event rings operate on a fast forwarding
mechanism where only the latest event is processed and the rest
are skipped. The recycle API only handles updating the
context write pointer in sequence which causes an out of bounds
doorbell issued to the device due to mismatched values. Add
another API to support handling updates for context write
pointer separately with the fast forwarding use case.

Change-Id: If628b49e063d14920fe734ebd113c9c4c733204b
Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>