Rework a little bit sensor_activate_virtual
Rework a little bit sensor_activate_virtual

Mostly cosmetic. Added a couple of traces too.

Change-Id: Ia8b8a0474421a25e077975d926d6a39518870297
Signed-off-by: Patrick Porlan <6b7a5b9114e07d350ffba0c179039885a7e82794@intel.com>

01org/android-iio-sensors-hal,01org/android-iio-sensors-hal