Camera: Add torch brightness control keys.

1.FLASH_INFO_STRENGTH_MAXIMUM_LEVEL : Number of brightness levels.
2.FLASH_INFO_STRENGTH_DEFAULT_LEVEL : Default brightness level for device in
TORCH mode.

bug: 200174275
Change-Id: I76618f8f4e091d30f12d0d00cfb8783c5e08645c
1 file changed