mhi: core: Treat MHI_ASSERT as fatal error

Currently MHI_ASSERT causes kernel panic in debug mode.
In performance mode it just prints warning and continues.
This can cause memory over-read, out of bound memory read.
All the places driver is asserting need to result into a
kernel panic to root cause the issue and prevent unwanted
memory access.

Change-Id: Ica8e1fec7be916621398cd4c5f8bfa6718c33d72
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>