at91bootstrap: remove manual copy of binaries to BIN_DIR

removed copying of binaries to BIN_DIR during install and using
default/install to install binaries to BIN_DIR folder.

Signed-off-by: Sandeep Sheriker Mallikarjun <sandeepsheriker.mallikarjun@microchip.com>

package/boot/at91bootstrap/at91bootstrap.mk

@@ -1,6 +1,15 @@
 
+PKG_TARGETS := bin
+PKG_FLAGS:=nonshared
+
 export GCC_HONOUR_COPTS=s
 
+define Package/at91bootstrap/install/default
+  $(CP) $(PKG_BUILD_DIR)/binaries/*uboot* $(1)/
+endef
+
+Package/at91bootstrap/install = $(Package/at91bootstrap/install/default)
+
 define AT91Bootstrap/Init
   BUILD_TARGET:=
   BUILD_SUBTARGET:=
@@ -46,8 +55,7 @@ define Build/AT91Bootstrap/Target
   endef
 
   define Package/at91bootstrap-$(1)/install
-    $(CP) $(PKG_BUILD_DIR)/binaries/*uboot*.bin \
-      $(BIN_DIR)/at91bootstrap-$(1).bin
+    $$(Package/at91bootstrap/install)
   endef
 endef