board: sl28: remove unneeded ddr config parameter

config_2 doesn't need to be set to zero because that is already the
default value.

Signed-off-by: Michael Walle <michael@walle.cc>
diff --git a/board/kontron/sl28/ddr.c b/board/kontron/sl28/ddr.c
index d75b23e..ed799c6 100644
--- a/board/kontron/sl28/ddr.c
+++ b/board/kontron/sl28/ddr.c
@@ -69,7 +69,6 @@
 		dram_size = 0x80000000;
 		ddr_cfg_regs.cs[1].bnds = 0;
 		ddr_cfg_regs.cs[1].config = 0;
-		ddr_cfg_regs.cs[1].config_2 = 0;
 		break;
 	case GPPORCR1_MEM_4GB_CS0_1:
 		dram_size = 0x100000000ULL;