pkg-download.mk: Add missing argument when downloading from primary mirror (scp)

This problem was already fixed by Markos Chandras for wget, but not for scp.

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/pkg-download.mk

@@ -206,7 +206,7 @@ endef
 define DOWNLOAD_INNER
 	$(Q)if test -n "$(call qstrip,$(BR2_PRIMARY_SITE))" ; then \
 		case "$(call geturischeme,$(BR2_PRIMARY_SITE))" in \
-			scp) $(call $(DL_MODE)_SCP,$(BR2_PRIMARY_SITE),$(2)) && exit ;; \
+			scp) $(call $(DL_MODE)_SCP,$(BR2_PRIMARY_SITE)/$(2),$(2)) && exit ;; \
 			*) $(call $(DL_MODE)_WGET,$(BR2_PRIMARY_SITE)/$(2),$(2)) && exit ;; \
 		esac ; \
 	fi ; \