'rx_macro_reg_mask_val' is unused since the original
commit af3d54b9 ("ASoC: codecs: lpass-rx-macro: add support for
lpass rx macro").

Remove it.
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Link: https://msgid.link/r/20240601225446.183505-2-linux@treblig.orgSigned-off-by: Mark Brown <broonie@kernel.org>