mhi: core: Error handling for pending packets in mission_mode

Clearing pending packets global reference count in mhi_controller
only when channel is in mission mode in error handling mechanism
with command completion timeout in mhi prepeare channel

Change-Id: Ib86b4f2a2ff5f28d27cf6174f65987d4f9ca1aea
Signed-off-by: Vivek Pernamitta <vpernami@codeaurora.org>