pinctrl: starfive: Use a static name for the GPIO irq_chip

pinctrl: starfive: Use a static name for the GPIO irq_chip

Drop the device name used for the GPIO irq_chip and replace it
with something static. The information is still available from
debugfs and carried as part of the irqdomain.

Suggested-by: Emil Renner Berthing <kernel@esmil.dk>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Link: https://lore.kernel.org/r/20220211092345.1093332-1-maz@kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>