mhi: core: fix iterating through misc offset for capabilities

Iterating through capabilities from MHI MISC offset registers
should be done in a way that the next offset can be directly
used.

CRs-Fixed: 2506085
Change-Id: I66b3d8b627a96d065b6eb30c1d0a21819d11c980
Acked-by: Bhaumik Vasav Bhatt <bbhatt@qti.qualcomm.com>
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>