mhi: core: Add support to allocate contiguous phys mem for bhie table

Contiguous phys memory is required per segment of the bhie table for
collecting rddm and fbc ram dumps.

Change-Id: Id21a34d4b22ed85cfa3fd559904c5a4602e5f8e7
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>