Audio: Up_down_mix: Add generic C process function

WIP - now only mono and stereo

Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>

Author: singalsu

src/audio/up_down_mixer/up_down_mixer_hifi3.c

@@ -1952,13 +1952,25 @@ void upmix32bit_2_0_to_7_1(struct up_down_mixer_data *cd, const uint8_t * const
 void shiftcopy32bit_mono(struct up_down_mixer_data *cd, const uint8_t * const in_data,
 			 const uint32_t in_size, uint8_t * const out_data)
 {
-	sof_panic(0);
+	size_t i;
+
+	int32_t *in_ptr = (int32_t *)in_data;
+	int32_t *out_ptr = (int32_t *)out_data;
+
+	for (i = 0; i < (in_size >> 2); ++i)
+		out_ptr[i] = in_ptr[i];
 }
 
 void shiftcopy32bit_stereo(struct up_down_mixer_data *cd, const uint8_t * const in_data,
 			   const uint32_t in_size, uint8_t * const out_data)
 {
-	sof_panic(0);
+	uint32_t i;
+
+	int32_t *in_ptr = (int32_t *)in_data;
+	int32_t *out_ptr = (int32_t *)out_data;
+
+	for (i = 0; i < (in_size >> 3); ++i)
+		out_ptr[i] = in_ptr[i];
 }
 
 void downmix32bit_2_1(struct up_down_mixer_data *cd, const uint8_t * const in_data,