ethtool: don't specify STRIPPROG

The correct strip program gets picked up at configure time, so no need to
specify it at target install time.

package/ethtool/ethtool.mk

@@ -10,7 +10,7 @@ ETHTOOL_SITE:=http://$(BR2_SOURCEFORGE_MIRROR).dl.sourceforge.net/sourceforge/gk
 ETHTOOL_AUTORECONF:=no
 ETHTOOL_INSTALL_STAGING:=NO
 ETHTOOL_INSTALL_TARGET:=YES
-ETHTOOL_INSTALL_TARGET_OPT:=DESTDIR=$(TARGET_DIR) STRIPPROG='$(STRIPCMD)' install-strip
+ETHTOOL_INSTALL_TARGET_OPT:=DESTDIR=$(TARGET_DIR) install-strip
 ETHTOOL_UNINSTALL_TARGET_OPT:=DESTDIR=$(TARGET_DIR) uninstall
 
 ETHTOOL_DEPENDENCIES:=uclibc