ASoC: tas2781: fix to save the dsp bin file name into the correct array in case name_prefix is not NULL

fix to save the dsp bin file name into the correct array, coef_binaryname,
instead of rca_binaryname, in case name_prefix is not NULL.
Signed-off-by: Shenghao Ding <shenghao-ding@ti.com>
Link: https://patch.msgid.link/20240907001540.944-1-shenghao-ding@ti.comSigned-off-by: Mark Brown <broonie@kernel.org>