mhi: core: ensure non-zero session or sequence ID values

While writing any sequence or session identifiers, it is
possible that the host could write a zero value, whereas only
non-zero values are supported writes to those registers. Ensure
that host does not write a non-zero value for those cases.

Change-Id: I33248a0aa43321c85a107e394f953774140dec50
Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>