driver core: platform: fix race condition with driver_override

driver core: platform: fix race condition with driver_override

The driver_override implementation is susceptible to race condition when
different threads are reading vs storing a different driver override.
Add locking to avoid race condition.

Fixes: 3d713e0e382e ("driver core: platform: add device binding path 'driver_override'")
Cc: stable@vger.kernel.org
Signed-off-by: Adrian Salido <salidoa@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 6265539776a0810b7ce6398c27866ddb9c6bd154)

Orabug: 27897874
CVE: CVE-2017-12146

Signed-off-by: Tim Tianyang Chen <tianyang.chen@oracle.com>
Reviewed-by: Jack Vogel <jack.vogel@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>