Using dev_err_probe() brings several improvements:

 - emits the symbolic error code
 - properly handles EPROBE_DEFER
 - combines error message generation and return value handling

While at it add error messages to two error paths that were silent
before.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>