spi: cs42l43: Drop cs35l56 SPI speed down to 11MHz

Some internals of the cs35l56 can only support SPI speeds of up to
11MHz. Whilst some use-cases could support higher rates, keep things
simple by dropping the SPI speed down to this avoid any potential
issues.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240607103423.4159834-1-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>