ALSA: fireface: code refactoring to add enumeration constants for model identification

In RME fireface series, version field of unit directory in configuration
ROM is used to distinguish each model. The value of field is known and
it's better to use enumeration constants for code representation.

This commit adds enumeration constants for model identification.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20200510074301.116224-4-o-takashi@sakamocchi.jpSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/fireface/ff.c

@@ -189,7 +189,7 @@ static const struct ieee1394_device_id snd_ff_id_table[] = {
 				  IEEE1394_MATCH_MODEL_ID,
 		.vendor_id	= OUI_RME,
 		.specifier_id	= OUI_RME,
-		.version	= 0x000001,
+		.version	= SND_FF_UNIT_VERSION_FF800,
 		.model_id	= 0x101800,
 		.driver_data	= (kernel_ulong_t)&spec_ff800,
 	},
@@ -201,7 +201,7 @@ static const struct ieee1394_device_id snd_ff_id_table[] = {
 				  IEEE1394_MATCH_MODEL_ID,
 		.vendor_id	= OUI_RME,
 		.specifier_id	= OUI_RME,
-		.version	= 0x000002,
+		.version	= SND_FF_UNIT_VERSION_FF400,
 		.model_id	= 0x101800,
 		.driver_data	= (kernel_ulong_t)&spec_ff400,
 	},
@@ -213,7 +213,7 @@ static const struct ieee1394_device_id snd_ff_id_table[] = {
 				  IEEE1394_MATCH_MODEL_ID,
 		.vendor_id	= OUI_RME,
 		.specifier_id	= OUI_RME,
-		.version	= 0x000004,
+		.version	= SND_FF_UNIT_VERSION_UCX,
 		.model_id	= 0x101800,
 		.driver_data	= (kernel_ulong_t)&spec_ucx,
 	},

sound/firewire/fireface/ff.h

@@ -34,6 +34,12 @@
 #define SND_FF_IN_MIDI_PORTS		2
 #define SND_FF_OUT_MIDI_PORTS		2
 
+enum snd_ff_unit_version {
+	SND_FF_UNIT_VERSION_FF800	= 0x000001,
+	SND_FF_UNIT_VERSION_FF400	= 0x000002,
+	SND_FF_UNIT_VERSION_UCX		= 0x000004,
+};
+
 enum snd_ff_stream_mode {
 	SND_FF_STREAM_MODE_LOW = 0,
 	SND_FF_STREAM_MODE_MID,