V4L/DVB (7613): em28xx: rename registers

Now, all registers will follow the same convension:

EM28XX_R<reg_number>_<reg_name>

This allows to associate a register with its value, and also with a canonical
name. Also, registers that are specific to a given chip were renamed accordingly,
as EM2800_foo (for 2800 only registers) or EM2880_foo (for registers that started
to appear on em2880).

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/drivers/media/video/em28xx/em28xx-video.c b/drivers/media/video/em28xx/em28xx-video.c
index a8aa09c..fb533fd 100644
--- a/drivers/media/video/em28xx/em28xx-video.c
+++ b/drivers/media/video/em28xx/em28xx-video.c
@@ -1142,9 +1142,9 @@
 static int em28xx_reg_len(int reg)
 {
 	switch (reg) {
-	case AC97LSB_REG:
-	case HSCALELOW_REG:
-	case VSCALELOW_REG:
+	case EM28XX_R40_AC97LSB:
+	case EM28XX_R30_HSCALELOW:
+	case EM28XX_R32_VSCALELOW:
 		return 2;
 	default:
 		return 1;