MIPS: Remove repetitive increase irq_err_count

commit 979934da ("[PATCH] mips: update IRQ handling for vr41xx") added
a function irq_dispatch, and it'll increase irq_err_count when the get_irq
callback returns a negative value, but increase irq_err_count in get_irq
was not removed.

And also, modpost complains once gpio-vr41xx drivers become modules.
  ERROR: modpost: "irq_err_count" [drivers/gpio/gpio-vr41xx.ko] undefined!

So it would be a good idea to remove repetitive increase irq_err_count in
get_irq callback.

Fixes: 27fdd325 ("MIPS: Update VR41xx GPIO driver to use gpiolib")
Fixes: 979934da ("[PATCH] mips: update IRQ handling for vr41xx")
Reported-by: k2ci <kernel-bot@kylinos.cn>
Signed-off-by: huhai <huhai@kylinos.cn>
Signed-off-by: Genjian Zhang <zhanggenjian@kylinos.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>