Fix "Widening multiply-accumulate operation uses wrong value extension"
for 4.7, 4.7-linaro and 4.6-linaro, which backported the broken code to 4.6.
Vanilla 4.6 is unaffected.
Fixes#13420.
Signed-off-by: Jonas Gorski <jogo@openwrt.org>
SVN-Revision: 36486
