ASoC: sam9g20_wm8731: Simplify some error message

ASoC: sam9g20_wm8731: Simplify some error message

dev_err_probe() already prints the error code in a human readable way, so
there is no need to duplicate it as a numerical value at the end of the
message.

Fixes: 29f4078f777f ("ASoC: sam9g20_wm8731: Use dev_err_probe() for snd_soc_register_card()")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/fb959b3bda689aa47e1fbe9948de957b77530b24.1659764734.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Mark Brown <broonie@kernel.org>