ASoC: doc: cs35l56: Update firmware filename description for B0 silicon

Update the text for firmware file naming to show that the l?u? suffix is
supported on CS35L56 B0 silicon and ampN was only used on early firmware.

The previous version of this text only said that B0 silicon used the ampN
suffix. Since kernel 6.16 the driver supports both the old ampN and
new l?u? suffix for B0 silicon. New firmwares will use the l?u? suffix.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://patch.msgid.link/20251103115809.33953-1-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: rfvirgil

Documentation/sound/codecs/cs35l56.rst

@@ -105,10 +105,10 @@ In this example the SSID is 10280c63.
 
 The format of the firmware file names is:
 
-SoundWire (except CS35L56 Rev B0):
+SoundWire:
     cs35lxx-b0-dsp1-misc-SSID[-spkidX]-l?u?
 
-SoundWire CS35L56 Rev B0:
+SoundWire CS35L56 Rev B0 firmware released before kernel version 6.16:
     cs35lxx-b0-dsp1-misc-SSID[-spkidX]-ampN
 
 Non-SoundWire (HDA and I2S):
@@ -127,9 +127,8 @@ Where:
   * spkidX is an optional part, used for laptops that have firmware
     configurations for different makes and models of internal speakers.
 
-The CS35L56 Rev B0 continues to use the old filename scheme because a
-large number of firmware files have already been published with these
-names.
+Early firmware for CS35L56 Rev B0 used the ALSA prefix (ampN) as the
+filename qualifier. Support for the l?u? qualifier was added in kernel 6.16.
 
 Sound Open Firmware and ALSA topology files
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