gstreamer1.0: update licenses of all modules

Since all gstreamer modules uses LGPLv2.1 with exceptions
for some plugins in bad and ugly modules that has GPLv2+.

Signed-off-by: Jose Quaresma <quaresma.jose@gmail.com>
Cc: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>