ASoC: Ux500: Correct license strings

GPLv2 -> GPL v2

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Ola Lilja <ola.o.lilja@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>