iio: accel: mma9553: add enable channel for activity
iio: accel: mma9553: add enable channel for activity

Add an enable channel for activity, so it can also
be polled independently of events or other channels.

Signed-off-by: Irina Tirdea <756d90dbe30c1aa83b724b214803f9c992482927@intel.com>
Reported-by: Daniel Baluta <f45a6396254d0683f1df8e14b691f61d753fe117@intel.com>
Signed-off-by: Jonathan Cameron <09f65b71b7655725897b2fd41a09a0cefe2e1ace@kernel.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs