[ Upstream commit 2439d37e1bf8a34d437573c086572abe0f3f1b15 ]

This patch fixes the following static checker warning:

drivers/input/keyboard/st-keyscan.c:156 keyscan_probe()
error: potential zalloc NULL dereference: 'keypad_data->input_dev'
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NGabriel Fernandez <gabriel.fernandez@st.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>