firmware: cs_dsp: Remove __free() from cs_dsp_debugfs_string_read()

firmware: cs_dsp: Remove __free() from cs_dsp_debugfs_string_read()

Don't use __free(kfree) in cs_dsp_debugfs_string_read. Instead use
normal kfree() to cleanup.

The use of __free() can create new cleanup bugs that are difficult to spot
because the defective code is idiomatically correct regular C. This
function used the suspect declaration __free(kfree) = NULL;.

The __free(kfree) didn't really do anything here. The function can be
rearranged to avoid any need to return or goto within the code.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: 3045e29d248b ("firmware: cs_dsp: Append \n to debugfs string during read")
Link: https://patch.msgid.link/20251202113425.413700-1-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>