Input: matrix_keypad - check for errors from of_get_named_gpio()

Input: matrix_keypad - check for errors from of_get_named_gpio()

commit d55bda1b3e7c5a87f10da54fdda866a9a9cef30b upstream.

"of_get_named_gpio()" returns a negative error value if it fails
and drivers should check for this. This missing check was now
added to the matrix_keypad driver.

In my case "of_get_named_gpio()" returned -EPROBE_DEFER because
the referenced GPIOs belong to an I/O expander, which was not yet
probed at the point in time when the matrix_keypad driver was
loading. Because the driver did not check for errors from the
"of_get_named_gpio()" routine, it was assuming that "-EPROBE_DEFER"
is actually a GPIO number and continued as usual, which led to further
errors like this later on:

WARNING: CPU: 3 PID: 167 at drivers/gpio/gpiolib.c:114
gpio_to_desc+0xc8/0xd0
invalid GPIO -517

Note that the "GPIO number" -517 in the error message above is
actually "-EPROBE_DEFER".

As part of the patch a misleading error message "no platform data defined"
was also removed. This does not lead to information loss because the other
error paths in matrix_keypad_parse_dt() already print an error.

Signed-off-by: Christian Hoff <christian_hoff@gmx.net>
Suggested-by: Sebastian Reichel <sre@kernel.org>
Reviewed-by: Sebastian Reichel <sre@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>