watchdog: hpwdt: Claim NMIs generated by iLO5

On iLO5 going forward we want to return and not claim the NMI, if
the NMI was NOT gnerated by the iLO as a result of the watchdog
timing out or an explicit generate NMI.

The sense of the test in is inverted and prevents hpwdt_pretimeout
from claiming NMIs when it should.

Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com>
Fixes: a042229a ("watchdog: hpwdt: Update nmi_panic message.")
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>