ASoC: WL1273 FM Radio: Eliminate unnecessary error return value.

With this change it's not a error to call wl1273_set_audio_route
when the codec is active if the new routing value is the same
as the current active setting.

Signed-off-by: Matti J. Aaltonen <matti.j.aaltonen@nokia.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>