gpio: nomadik: Add missing IS_ERR() check

gpio: nomadik: Add missing IS_ERR() check

[ Upstream commit 58433885ee99e8c96757e82ccf6d50646c4dfe09 ]

The function gpio_device_get_desc() can return an error pointer and is
not checked for one. Add check for error pointer.

Fixes: ddeb66d2cb10f ("gpio: nomadik: don't print out global GPIO numbers in debugfs callbacks")
Cc: stable@vger.kernel.org
Signed-off-by: Ethan Tidmore <ethantidmore06@gmail.com>
Link: https://patch.msgid.link/20260214044531.43539-1-ethantidmore06@gmail.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>