ASoC: cs35l41: Update handling of test key registers

ASoC: cs35l41: Update handling of test key registers

In preparation for the addition of PM runtime support move the test
key out of the register patches themselves. This is necessary to
allow the test key to be held during cache synchronisation, which is
required by the OTP settings which were unpacked from the device and
written by the driver.

Also whilst at it, the driver uses a mixture of accessing the test key
register by name and by address, consistently use the name.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20220107160636.6555-2-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>