Change all '$(...)' variable references into '${...}'
which makes the environment compatible with the hush shell.
WARNING: Support for the old '$(...)' syntax will be
discontinued in a later version.
diff --git a/board/esd/plu405/plu405.c b/board/esd/plu405/plu405.c
index 16f2360..5b9d063 100644
--- a/board/esd/plu405/plu405.c
+++ b/board/esd/plu405/plu405.c
@@ -54,7 +54,7 @@
 au_image_t au_image[] = {
 	{"plu405/preinst.img", 0, -1, AU_SCRIPT},
 	{"plu405/u-boot.img", 0xfffc0000, 0x00040000, AU_FIRMWARE},
-	{"plu405/pImage_$(bd_type)", 0x00000000, 0x00100000, AU_NAND},
+	{"plu405/pImage_${bd_type}", 0x00000000, 0x00100000, AU_NAND},
 	{"plu405/pImage.initrd", 0x00100000, 0x00200000, AU_NAND},
 	{"plu405/yaffsmt2.img", 0x00300000, 0x01c00000, AU_NAND},
 	{"plu405/postinst.img", 0, 0, AU_SCRIPT},