ASoC: wm8731: Factor component init out of bus code

Both the I2C and SPI bus code register the component immediately after they
call wm8731_hw_init(), factor the code out into the the common function and
rename it to just be plain wm8731_init() while we're at it since it's not
just for hardware init any more. This refactoring means we need to move the
function after the declaration of the component driver.

Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20220325153121.1598494-3-broonie@kernel.org


Signed-off-by: Mark Brown <broonie@kernel.org>