V4L/DVB (9761): em28xx: replace magic numbers for mux aliases

Instead of using magic vmux/amux, let's use an alias where possible.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/em28xx/em28xx-cards.c

@@ -315,15 +315,15 @@ struct em28xx_board em28xx_boards[] = {
 		.decoder      = EM28XX_SAA711X,
 		.input        = { {
 			.type     = EM28XX_VMUX_TELEVISION,
-			.vmux     = 2,
+			.vmux     = SAA7115_COMPOSITE2,
 			.amux     = EM28XX_AMUX_VIDEO,
 		}, {
 			.type     = EM28XX_VMUX_COMPOSITE1,
-			.vmux     = 0,
+			.vmux     = SAA7115_COMPOSITE0,
 			.amux     = EM28XX_AMUX_LINE_IN,
 		}, {
 			.type     = EM28XX_VMUX_SVIDEO,
-			.vmux     = 9,
+			.vmux     = SAA7115_COMPOSITE0,
 			.amux     = EM28XX_AMUX_LINE_IN,
 		} },
 	},
@@ -623,7 +623,7 @@ struct em28xx_board em28xx_boards[] = {
 		}, {
 			.type     = EM28XX_VMUX_COMPOSITE1,
 			.vmux     = TVP5150_COMPOSITE1,
-			.amux     = 3,
+			.amux     = EM28XX_AMUX_LINE_IN,
 			.gpio     = hauppauge_wintv_hvr_900_analog,
 		}, {
 			.type     = EM28XX_VMUX_SVIDEO,