s390: Update defconfigs which were missing CONFIG_NET.

Commit df568d8e ("scsi: Use 'depends' with LIBFC instead of
'select'.")  removed what happened to be the only instance of 'select
NET'. Defconfigs that were relying on the select now lack networking
support.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/s390/configs/performance_defconfig b/arch/s390/configs/performance_defconfig
index 61db449..13559d3 100644
--- a/arch/s390/configs/performance_defconfig
+++ b/arch/s390/configs/performance_defconfig
@@ -59,6 +59,7 @@
 # CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS is not set
 CONFIG_BINFMT_MISC=m
 CONFIG_HIBERNATION=y
+CONFIG_NET=y
 CONFIG_PACKET=y
 CONFIG_PACKET_DIAG=m
 CONFIG_UNIX=y