s390x: unittests: Use smp parameter

Signed-off-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Message-Id: <20200403094015.506838-1-drjones@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>

s390x/unittests.cfg

diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
index 535db21..b307329 100644
--- a/s390x/unittests.cfg
+++ b/s390x/unittests.cfg
@@ -75,7 +75,7 @@
 
 [smp]
 file = smp.elf
-extra_params =-smp 2
+smp = 2
 
 [sclp-1g]
 file = sclp.elf