wext: Re-add support for SIGNAL_POLL and DRIVER

Both of these are still used by JB, and wext wifi drivers have some
weird behaviors without it (like a reported poor connection 100% of
the time)

Change-Id: I15339dbea4e15831465e2bb52b11675cb20dc34c
Merge remote-tracking branch 'cm/cm-10.1' into HEAD
Fixed issues in nl80211 driver.

Signed-off-by: Chuck Haines <chaines@codemonkeyjava.com>