Staging: ipack/devices/ipoctal: remove unneeded lock in IRQ handler

In the rest of the code, the data is protected with spin_lock_irqsave().

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>