pinctrl: at91-pio4: fix domain name assignment

Since commit d59f6617 ("genirq: Allow fwnode to carry name
information only") an IRQ domain is always given a name during
allocation (e.g. used for the debugfs entry).

Drop the no longer valid name assignment, which would lead to an attempt
to free a string constant when removing the domain on late probe
failures (e.g. probe deferral).

Fixes: d59f6617

 ("genirq: Allow fwnode to carry name information only")
Cc: stable@vger.kernel.org	# 4.13
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Tested-by: Claudiu Beznea <claudiu.beznea@microchip.com> # on SAMA7G5
Link: https://lore.kernel.org/r/20230224130828.27985-1-johan+linaro@kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>