lua: fix typo

Commit c8da6d1dd656caf5454c50ee5dddb4beead60326 introduced a stupid
typo. Fix it.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/lua/lua.mk

@@ -85,7 +85,7 @@ define LUA_INSTALL_LIBRARY
 endef
 else
 define LUA_INSTALL_LIBRARY
-	$(INSTALL) -m 0644 -D$(@D)/src/liblua.a $(TARGET_DIR)/usr/lib/liblua.a
+	$(INSTALL) -m 0644 -D $(@D)/src/liblua.a $(TARGET_DIR)/usr/lib/liblua.a
 endef
 endif