Camera: Fix up torch strength keys.

Fix up new camera characteristics keys for torch strength control API
and update default value 1 for ANDROID_FLASH_INFO_STRENGTH_DEFAULT_LEVEL
and ANDROID_FLASH_INFO_STRENGTH_MAXIMUM_LEVEL.
These keys will only be updated if the camera device has flash unit.

Bug: 189470637

Test: Tested on Pixel 4XL and verified that the keys were added with
default value 1.

Change-Id: I060717b793b4598fea9688453f44a85e8b2b1c2b