Change: Hide biometrical if device does not support it

Biometric lock preference in "Security" settings subsection was shown even when the
device didn't support biometrics (if it was Android 6.0 or later versions). Now, the
preference is only shown if the device has the suitable hardware for it.

https://github.com/owncloud/android/issues/3217 https://github.com/owncloud/android/pull/3230
