gpio: grgpio: call request_irq after incrementing the reference count

gpio: grgpio: call request_irq after incrementing the reference count

Remove extraneous dropping of the lock just to call 'request_irq'
and locking again afterwards. Increment reference count
before calling 'request_irq'. Rollback reference count if
'request_irq' fails.

Suggested-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Alex Tran <alex.t.tran@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>