ALSA: scarlett2: Change num_mux_* from int to u8

num_mux_srcs and num_mux_dsts will fit into a u8, so change the type.
More similar counts are coming soon.
Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Link: https://lore.kernel.org/r/886fbd9ce7f06b13c6dbf36f64e6b2d107d16a83.1703444932.git.g@b4.vuSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/mixer_scarlett2.c

@@ -607,8 +607,8 @@ struct scarlett2_data {
 	__u8 bEndpointAddress;
 	__u16 wMaxPacketSize;
 	__u8 bInterval;
-	int num_mux_srcs;
-	int num_mux_dsts;
+	u8 num_mux_srcs;
+	u8 num_mux_dsts;
 	u32 firmware_version;
 	u8 flash_segment_nums[SCARLETT2_SEGMENT_ID_COUNT];
 	u8 flash_segment_blocks[SCARLETT2_SEGMENT_ID_COUNT];