MIPS: irq: Remove IRQF_DISABLED

Since commit [e58aa3d2: genirq: Run irq handlers with interrupts disabled],
We run all interrupt handlers with interrupts disabled and we even check
and yell when an interrupt handler returns with interrupts enabled (see
commit [b738a50a: genirq: Warn when handler enables interrupts]).

So now this flag is a NOOP and can be removed.

[ralf@linux-mips.org: Fixed up conflicts in
arch/mips/alchemy/common/dbdma.c, arch/mips/cavium-octeon/smp.c and
arch/mips/kernel/perf_event.c.]

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: tglx@linutronix.de
linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2835/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>