opus-tools: update license

As per COPYING file, opusinfo is licensed under GPL version 2.

Signed-off-by: Rahul Bedarkar <rahulbedarkar89@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/opus-tools/opus-tools.mk

@@ -6,7 +6,7 @@
 
 OPUS_TOOLS_VERSION = 0.1.10
 OPUS_TOOLS_SITE = https://downloads.xiph.org/releases/opus
-OPUS_TOOLS_LICENSE = BSD-2-Clause
+OPUS_TOOLS_LICENSE = BSD-2-Clause, GPL-2.0 (opusinfo)
 OPUS_TOOLS_LICENSE_FILES = COPYING
 OPUS_TOOLS_CONF_OPTS = --disable-oggtest --disable-opustest
 OPUS_TOOLS_DEPENDENCIES = opus libogg host-pkgconf