msm: cam: reqmgr: Add uapi header for camera request manager

Add the required structure definitions for the camera request
manager driver. These changes include IOCTL definitions, op codes,
and payload information. These definitions will allow user space
to make IOCTL calls into the request manager driver.

CRs-Fixed: 1108532
Change-Id: Ie186a48497619b50560241067f917712936b1f2a
Signed-off-by: Sagar Gore <sgore@codeaurora.org>
Signed-off-by: Hariram Purushothaman <hariramp@codeaurora.org>
Signed-off-by: Jing Zhou <jzhou70@codeaurora.org>