Torch: add 2nd sysfs luminosity

Change-Id: Iedc172984bb20c0a4a073a8cbf5f0f008aa57c38
Fix crash of torch app

A hard to track bug occurs when using the torch:
The local variable surfaceTexture gets collected by GC causing it
to free the underlying buffer.
The next access to this buffer crashes with an SIGSEGV after an
assertion failure (BufferQueue already abandoned)

NOTE: The native camera object may possibly hold that reference so
it does not get GC'ed

Change-Id: Ib39d55ffb379ed16a0b94915c1b727e8ddc7f180
(cherry picked from commit 450b3bd93a772d5c7c464842c5806f5abd5c8ad2)