layerscape: define only one package for ls-rcw

We do not have to define package for each board, and
consider variant's building/installing.
It is easier to maintain ls-rcw with only one package
installing all boards RCW binaries as intermediate
files, each of which is just about hundreds of bytes.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>

package/boot/tfa-layerscape/Makefile

@@ -25,7 +25,7 @@ define Package/tfa-layerscape/Config
     SECTION:=boot
     CATEGORY:=Boot Loaders
     TITLE:=$(2)
-    DEPENDS:=@TARGET_layerscape_armv8_64b +layerscape-rcw-$(1)
+    DEPENDS:=@TARGET_layerscape_armv8_64b +layerscape-rcw
     HIDDEN:=1
     VARIANT:=$(1)
     BIN_BL2:=$(3)