rp-pppoe: bail out if installation fails

Add an "|| exit 1" in the installation loop, otherwise if one of the
file fails to install, the build doesn't abort.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/rp-pppoe/rp-pppoe.mk

@@ -19,7 +19,7 @@ RP_PPPOE_CONF_ENV = \
 
 define RP_PPPOE_INSTALL_TARGET_CMDS
 	for ff in $(RP_PPPOE_TARGET_FILES); do \
-		$(INSTALL) -m 0755 $(@D)/src/$$ff $(TARGET_DIR)/usr/sbin/$$ff; \
+		$(INSTALL) -m 0755 $(@D)/src/$$ff $(TARGET_DIR)/usr/sbin/$$ff || exit 1; \
 	done
 endef