linuxdriver: check supplicant status before send message [1/1]

PD#TV-5392

Problem:
when playing netflix movies, press power button, TV can not
power down and console hang.

Solution:
1. check supplicant status before send message

Test: manual - mm

Verify:
TXLX + Android P

Change-Id: Ia4829ba22de97ee06273632f7b824ddfa5909ee4
Signed-off-by: Pengguang Zhu <pengguang.zhu@amlogic.com>