freescale: pblimage: refactor CONFIG_SYS_FSL_PBL_{PBI, RCW}

Pull out "$(SRCTREE)/" from CONFIG_SYS_FSL_PBL_PBI
and CONFIG_SYS_FSL_PBL_RCW and push it into the top Makefile.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: York Sun <yorksun@freescale.com>
Cc: Poonam Aggrwal <poonam.aggrwal@freescale.com>
Cc: Valentin Longchamp <valentin.longchamp@keymile.com>
diff --git a/include/configs/T1040QDS.h b/include/configs/T1040QDS.h
index e776a46..993f9ae 100644
--- a/include/configs/T1040QDS.h
+++ b/include/configs/T1040QDS.h
@@ -32,8 +32,8 @@
 #ifdef CONFIG_RAMBOOT_PBL
 #define CONFIG_RAMBOOT_TEXT_BASE	CONFIG_SYS_TEXT_BASE
 #define CONFIG_RESET_VECTOR_ADDRESS	0xfffffffc
-#define CONFIG_SYS_FSL_PBL_PBI $(SRCTREE)/board/freescale/t1040qds/t1040_pbi.cfg
-#define CONFIG_SYS_FSL_PBL_RCW $(SRCTREE)/board/freescale/t1040qds/t1040_rcw.cfg
+#define CONFIG_SYS_FSL_PBL_PBI board/freescale/t1040qds/t1040_pbi.cfg
+#define CONFIG_SYS_FSL_PBL_RCW board/freescale/t1040qds/t1040_rcw.cfg
 #endif
 
 /* High Level Configuration Options */