m7: camera: fix hardware hdr the dirty way

aosp expects hdr to be a scene-mode,
on our hal it's a capture-mode.

let's play some ping-pong.

Change-Id: Idc2e12eeb3a63fe8b1d5755d51887fe976df7bca
Merge "m7: camera: fix hardware hdr the dirty way" into cm-10.1