opkg: fix stray printf() (#551)

Update to latest Git head to get rid of a stray printf() causing unwanted
output in the "opkg list-upgradable" command.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

package/system/opkg/Makefile

@@ -15,9 +15,9 @@ PKG_RELEASE:=1
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL:=https://git.lede-project.org/project/opkg-lede.git
-PKG_SOURCE_DATE:=2017-02-22
-PKG_SOURCE_VERSION:=271d485c10f2070573b25e740b93839945dbcd9d
-PKG_MIRROR_HASH:=f48fcbc9f509629aec30bca6aeaf78d831c9a041ac87468f7429d20361384ca9
+PKG_SOURCE_DATE:=2017-02-23
+PKG_SOURCE_VERSION:=f9baf914f8fd0179e575deeebabe463d9f87e850
+PKG_MIRROR_HASH:=ca5df4dc8b2a2dd2c37b1ed2f6a075661c54586f553e8cd056e93021e67c2e83
 
 PKG_LICENSE:=GPL-2.0
 PKG_LICENSE_FILES:=COPYING