ASoC: cs-amp-lib: Fix missing dput() after debugfs_lookup()

ASoC: cs-amp-lib: Fix missing dput() after debugfs_lookup()

Rewrite cs_amp_create_debugfs() so that dput() will be called on
a valid dentry returned from debugfs_lookup().

The pointer returned from debugfs_lookup() must be released by dput().
The pointer returned from debugfs_create_dir() does not need to be
passed to dput().

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: cdd27fa3298a ("ASoC: cs-amp-lib: Add helpers for factory calibration")
Link: https://patch.msgid.link/20260521122511.987322-3-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>