Camera: support torch control on external camera

Claim torch API support though there is no device
actually has a flash unit. This is to workaround
an issue in camera service where it falls back
to legacy camera HAL1 control if the device does
not report torch API support (and external camera
HAL does not implement HAL1)

Test: CtsVerifier FlashLight test
Bug: 113336515
Change-Id: I945b35fecfed3b2698b1e9bb1d8faad8699258d2