gmr1_rx: Don't try to low pass frequency correction
gmr1_rx: Don't try to low pass frequency correction

Some receivers (like rtl-sdr) have fast changes in the frequency
error, especially while they're warming up and this prevents good
tracking.

Signed-off-by: Sylvain Munaut <349f318521b45672c77207abf1a5ed60eb011db1@246tNt.com>

marcelmaatkamp/gnuradio-osmocom-gmr,marcelmaatkamp/docker-gnuradio-osmocom-gmr,marcelmaatkamp/docker-gnuradio-osmocom-gmr,marcelmaatkamp/docker-gnuradio-osmocom-gmr,marcelmaatkamp/gnuradio-osmocom-gmr,marcelmaatkamp/gnuradio-osmocom-gmr