Bluetooth: controller: Fix race waiting for ticker job to complt

Same volatile status variable as return and being updated
in ISR would modify the variable in two context which
caused the variable to be set to a stale value.

This commit uses two different variables, one for return
value and the other to be updated by ISR.

Jira: ZEP-1941

Change-id: I19e3bdc85e15bda7891395f3f1f64c2ddbeee0c6
Signed-off-by: Vinayak Chettimada <vinayak.kariappa.chettimada@nordicsemi.no>