amd/fam10: Fix pstate configuration

Testing for msr.hi | PS_EN_MASK doesn't make sense.

Change-Id: If3305e4255f227be4bb7a5496a625ef2a50a5808
Found-by: Coverity Scan
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: http://review.coreboot.org/7578
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Tested-by: build bot (Jenkins)
1 file changed