tty/serial: kill off set_irq_flags usage

set_irq_flags is ARM specific with custom flags which have genirq
equivalents. Convert drivers to use the genirq interfaces directly, so we
can kill off set_irq_flags. The translation of flags is as follows:

IRQF_VALID -> !IRQ_NOREQUEST
IRQF_PROBE -> !IRQ_NOPROBE
IRQF_NOAUTOEN -> IRQ_NOAUTOEN

For IRQs managed by an irqdomain, the irqdomain core code handles clearing
and setting IRQ_NOREQUEST already, so there is no need to do this in
.map() functions and we can simply remove the set_irq_flags calls. Some
users also set IRQ_NOPROBE and this has been maintained although it is not
clear that is really needed. There appears to be a great deal of blind
copy and paste of this code.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Barry Song <baohua@kernel.org>
Cc: linux-serial@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>