Smatch found a potential null dereference in gpio_setup_irq(). The
"pdesc" variable is allocated with idr_find() that can return NULL. If
gpio_setup_irq() is called with 0 as gpio_flags and "pdesc" is null, it
would OOPs here.
Signed-off-by: Dan Carpenter <error27@gmail.com> Cc: David Brownell <david-b@pacbell.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>