Preset loaded from SD: use its RBW (issue #97)

Loading a preset from SD did not call update_rbw() as caldata_recall()
does, so the RBW menu showed the preset's RBW while the sweep kept using
the previous one.

Tested on a ZS407: preset stored with RBW 30 kHz, RBW set to 300 kHz,
preset loaded from SD: "rbw" and the status panel show 30 kHz.
tinySA Ultra only, +4 B.

vna_browser.c

@@ -334,6 +334,7 @@ static char cmd_buffer[256+128];
       set_scale(setting.scale);
       set_reflevel(setting.reflevel);
       set_level_meter_or_waterfall();
+      update_rbw();                     // as caldata_recall(), else the RBW of the loaded preset is not used
       // Remember where this preset came from so storing it back can default to it
       plot_printf(sd_preset_path, sizeof(sd_preset_path), "%s", fno.fname);
     }