ASoC: cs35l56: Log a message if firmware is missing

ASoC: cs35l56: Log a message if firmware is missing

If the amp is still reporting FIRMWARE_MISSING after cs35l56_patch()
has completed it is helpful to log a warning.

After a complete firmware download the FIRMWARE_MISSING flag will be
clear. If this isn't the case, the driver should log a message to
report this.

The amp can produce basic audio output without firmware, as a fallback,
so this wasn't originally logged as a warning condition because the amp
is still in an operational state - just not with full functionality.
However, it was not at all obvious to an end user that anything is
unusual.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://patch.msgid.link/20251128112520.40067-1-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>