armv8: layerscape: add missing RCW source defines

A board might need to get the source of the RCW word, which is also the
boot source in most cases.

These defines are taken from the LS1028A and I expect they are the same
across the SoCs with the same chassis, after all, there was already a
reset source for NOR flash.

Signed-off-by: Michael Walle <michael@walle.cc>
diff --git a/arch/arm/include/asm/arch-fsl-layerscape/immap_lsch3.h b/arch/arm/include/asm/arch-fsl-layerscape/immap_lsch3.h
index 863618a..304cd79 100644
--- a/arch/arm/include/asm/arch-fsl-layerscape/immap_lsch3.h
+++ b/arch/arm/include/asm/arch-fsl-layerscape/immap_lsch3.h
@@ -230,6 +230,10 @@
 #define DCFG_BASE		0x01e00000
 #define DCFG_PORSR1			0x000
 #define DCFG_PORSR1_RCW_SRC		0xff800000
+#define DCFG_PORSR1_RCW_SRC_SDHC1	0x04000000
+#define DCFG_PORSR1_RCW_SRC_SDHC2	0x04800000
+#define DCFG_PORSR1_RCW_SRC_I2C		0x05000000
+#define DCFG_PORSR1_RCW_SRC_FSPI_NOR	0x07800000
 #define DCFG_PORSR1_RCW_SRC_NOR		0x12f00000
 #define DCFG_RCWSR12			0x12c
 #define DCFG_RCWSR12_SDHC_SHIFT		24