serial: 8250_exar: Avoid NULL pointer dereference at ->exit()

It's possible that during ->exit() the private_data is NULL,
for instance when there was no GPIO device instantiated.
Due to this we may not dereference it. Add a respective check.

Note, for now ->exit() only makes sense when GPIO device
was instantiated, that's why we may use the check for entire
function.

Fixes: 81171e7d31a6 ("serial: 8250_exar: Constify the software nodes")
Reported-by: Maxim Levitsky <[email protected]>
Signed-off-by: Andy Shevchenko <[email protected]>
Tested-by: Maxim Levitsky <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

0 files changed, 0 insertions, 0 deletions