rta: fix phase cpus assignment
rta: fix phase cpus assignment

Fix: The cpus of the phase of a task was never assigned in the
case where the cpu was given as an int and has the value 0.

Signed-off-by: Elieva Pignat <44a5274bcc440d4777a3c4474202e15e583e8208@arm.com>

ARM-software/lisa,ARM-software/lisa,credp/lisa,credp/lisa,ARM-software/lisa,credp/lisa,credp/lisa,ARM-software/lisa