rilmodem: set android properties if available

Supported so far:
 * gsm.network.type
 * gsm.sim.operator.alpha
 * gsm.sim.operator.iso-country
 * gsm.sim.operator.numeric
 * gsm.sim.state
 * gsm.version.baseband

Signed-off-by: You-Sheng Yang <vicamo@gmail.com>