As reported by smatch:
	drivers/media/usb/dvb-usb-v2/mxl111sf-demod.c:485 mxl111sf_demod_read_signal_strength() error: uninitialized symbol 'modulation'.
The mxl111sf_demod_read_signal_strength() just ignores if something
gets wrong while reading snr or modulation.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
 {
        struct mxl111sf_demod_state *state = fe->demodulator_priv;
        enum fe_modulation modulation;
+       int ret;
        u16 snr;
 
-       mxl111sf_demod_calc_snr(state, &snr);
-       mxl1x1sf_demod_get_tps_modulation(state, &modulation);
+       ret = mxl111sf_demod_calc_snr(state, &snr);
+       if (ret < 0)
+               return ret;
+       ret = mxl1x1sf_demod_get_tps_modulation(state, &modulation);
+       if (ret < 0)
+               return ret;
 
        switch (modulation) {
        case QPSK: