gpio: drop users of irq_set_chip_and_handler_name()

Switch all users of irq_set_chip_and_handler_name() to simply
use irq_set_chip_and_handler(), all just provide a boilerplate
name like "demux" or "mux" - a fact which is anyway obvious
from the hwirq number from the irqdomain now present in e.g.
/proc/interrupts.

Cc: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: David Cohen <david.a.cohen@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>