watchdog: Octeon: Mark octeon_wdt interrupt as IRQF_NO_THREAD

This is to exclude it from force threading to allow RT patch set to work.

The watchdog timers are per-CPU and the addresses of register that reset
the timer are calculated based on the current CPU.  Therefore we cannot
allow it to run on a thread on a different CPU.  Also we only do a
single register write, which is much faster than scheduling a handler
thread.

And while on this line remove IRQF_DISABLED as this flag is a NOP.

Signed-off-by: Venkat Subbiah<venkat.subbiah@cavium.com>
Acked-by: David Daney<david.daney@cavium.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>