dev/psci: Check all compat strings

When searching for the PSCI FDT node we only check a few compat strings.
Use the existing compat_data array to check all strings the driver may
attach to.

Sponsored by: Arm Ltd
Differential Revision: https://reviews.freebsd.org/D44913

(cherry picked from commit f91e9401c2098ba56f43093ef9747d0b1f60f8eb)