[media] dvb-frontends/drxk: don't log errors on unsupported operation mode

When fe_ops.read_status is called and no channel is tuned (yet), the
subsequent calls to get_lock_status() causes the kernel log to be filled
with

    drxk: Error -22 on get_lock_status

which either means a NULL pointer was passed for the p_lock_status var,
or neither QAM nor OFDM/DVBT operation mode are active. Instead of
filling the kernel log in the latter case, print out a message to the debug
level and return 0 (this isn't used in the calling drxk_get_stats() anyway).
Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/dvb-frontends/drxk_hard.c

@@ -1904,7 +1904,9 @@ static int get_lock_status(struct drxk_state *state, u32 *p_lock_status)
 		status = get_dvbt_lock_status(state, p_lock_status);
 		break;
 	default:
-		break;
+		pr_debug("Unsupported operation mode %d in %s\n",
+			state->m_operation_mode, __func__);
+		return 0;
 	}
 error:
 	if (status < 0)