gpio: zynq: Remove error prints in EPROBE_DEFER

In case of probe is deferred do not print the errors.

Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>