mhi: core: add support for collecting device ram dump during panic

For debugging purpose, we'd like to collect device ram dump
context when kernel panic happens. This patch adds support
for such requirement.

CRs-Fixed: 2221004
Change-Id: Ie0e829bd53f777da8d7d94e3261f2f7668e7a844
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>