V4L/DVB: dib7770: enable the current mirror

To improve performance on DiB7770-devices enabling the current mirror
is needed.

This patch adds an option to the dib7000p-driver to do that and it
creates a separate device-entry in dib0700-device to use those changes
on hardware which is using the DiB7770.

Signed-off-by: Olivier Grenie <olivier.grenie@dibcom.fr>
Signed-off-by: Patrick Boettcher <patrick.boettcher@dibcom.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/dvb/frontends/dib7000p.h b/drivers/media/dvb/frontends/dib7000p.h
index 805dd13..04a7449 100644
--- a/drivers/media/dvb/frontends/dib7000p.h
+++ b/drivers/media/dvb/frontends/dib7000p.h
@@ -33,6 +33,9 @@
 	int (*agc_control) (struct dvb_frontend *, u8 before);
 
 	u8 output_mode;
+
+	u8 enable_current_mirror : 1;
+
 };
 
 #define DEFAULT_DIB7000P_I2C_ADDRESS 18