spi: Fix spelling mistake "softwade" -> "software"

There is a spelling mistake in a dev_err message. Fix it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20210317093936.5572-1-colin.king@canonical.com


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