Restore default init values as init_v2

The addition of init_v3 accidentely changed default values for soft
resetting Ethos-U. Restore the default parameters to non-secure, user
mode for init_v1 and init_v2 and also make sure to check return value
from ethosu_soft_reset.

Change-Id: If7377f11ad1db7ff988fdcba03320a54e6e0c0c1