USB: rmnet: Free device context memory only during cleanup

Device context is currently allocated only once during
initialization and it gets freed during function unbind.
This causes memory corruption issue as device context is
accessed again after compostion switch.
Fix this issue by freeing the memory only at the time of
cleaning up the function driver resources.

Signed-off-by: Manu Gautam <mgautam@codeaurora.org>
2 files changed