soc: qcom: minidump: Add md_get_region function

Add a function md_get_region which returns md_region
when we pass minidump entry name to it.

Change-Id: Ibbd84737041c5b1c25cc46b9c740d415978de7e6
Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org>