msm: msm_bus: Fix commit bit being set at wrong index

Correct the index count when setting the commit bit on
tcs command sets in the case where the final BCM listed in
VCD is not part of the ACTIVE command set.

Change-Id: I183327c0046498387085b53457d1f7834f10e1d9
Signed-off-by: David Dai <daidavid1@codeaurora.org>