ALSA: scarlett2: Fix DSP filter control array handling

ALSA: scarlett2: Fix DSP filter control array handling

scarlett2_add_dsp_ctls() was incorrectly storing the precomp and PEQ
filter coefficient control pointers into the precomp_flt_switch_ctls
and peq_flt_switch_ctls arrays instead of the intended targets
precomp_flt_ctls and peq_flt_ctls. Pass NULL instead, as the filter
coefficient control pointers are not used, and remove the unused
precomp_flt_ctls and peq_flt_ctls arrays from struct scarlett2_data.

Additionally, scarlett2_update_filter_values() was reading
dsp_input_count * peq_flt_count values for
SCARLETT2_CONFIG_PEQ_FLT_SWITCH, but the peq_flt_switch array is
indexed only by dsp_input_count (one switch per DSP input, not per
filter). Fix the read count.

Fixes: b64678eb4e70 ("ALSA: scarlett2: Add DSP controls")
Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Link: https://patch.msgid.link/86497b71db060677d97c38a6ce5f89bb3b25361b.1771581197.git.g@b4.vu
Signed-off-by: Takashi Iwai <tiwai@suse.de>