Merge pull request #338 from FrankBoesing/patch-4

fix warnings

input_i2s.cpp

 			dest_left = &(left->data[offset]);
 			dest_right = &(right->data[offset]);
 			AudioInputI2S::block_offset = offset + AUDIO_BLOCK_SAMPLES/2;
-			arm_dcache_delete(src, sizeof(i2s_rx_buffer) / 2);
+			arm_dcache_delete((void*)src, sizeof(i2s_rx_buffer) / 2);
 			do {
 				*dest_left++ = *src++;
 				*dest_right++ = *src++;

input_i2s2.cpp

 			dest_right = &(right->data[offset]);
 			AudioInputI2S2::block_offset = offset + AUDIO_BLOCK_SAMPLES/2;
 
-			arm_dcache_delete(src, sizeof(i2s2_rx_buffer) / 2);
+			arm_dcache_delete((void*)src, sizeof(i2s2_rx_buffer) / 2);
 
 			do {
 				*dest_left++ = *src++;