ASoC: rsnd: enable SRC sync even FIN = FOUT

Current SRC (= Sampling Rate Converter) is supporting
SYNC mode and ASYNC mode. Current src.c cares SRC if FIN != FOUT.
Here, SYNC mode will be used for tweak, so it will be used
even FIN = FOUT. This patch enables SRC sync in such situation

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>
Tested-by: Yuichi Takagi <yuichi.takagi.uh@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>