V4L/DVB (13974): [STV090x] Fix locking reliabilty issues in automatic mode.

In automatic S/S2 detection mode, locking of a DVB-S transponder could
fail when coming from a DVB-S2 transponder. This change fixes the issue
by first disabling DVB-S and DVB-S2 mode before enabling it again.

Signed-off-by: Andreas Regel <[e-mail]>
Signed-off-by: Manu Abraham <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/dvb/frontends/stv090x.c

···
 	default:
 		/* enable DVB-S2 and DVB-S2 in Auto MODE */
 		reg = STV090x_READ_DEMOD(state, DMDCFGMD);
+		STV090x_SETFIELD_Px(reg, DVBS1_ENABLE_FIELD, 0);
+		STV090x_SETFIELD_Px(reg, DVBS2_ENABLE_FIELD, 0);
+		if (STV090x_WRITE_DEMOD(state, DMDCFGMD, reg) < 0)
+			goto err;
 		STV090x_SETFIELD_Px(reg, DVBS1_ENABLE_FIELD, 1);
 		STV090x_SETFIELD_Px(reg, DVBS2_ENABLE_FIELD, 1);
 		if (STV090x_WRITE_DEMOD(state, DMDCFGMD, reg) < 0)