watchdog: omap: simplify assignment of bootstatus

Instead of using an over-long expression involving the ?: operator use
an if and instead of an else branch rely on the fact that the data
structure was allocated using devm_kzalloc. This also allows to put the
used helper variable into a more local scope.

There is no functional change.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>