Incorrect (un-modified) frequency shown when closing the help dialog.

[philcrump]

Steps to reproduce:

• Open lora-gateway (eg. on 434.450)
• Press 'd'/'D' twice to tune upwards 2 KHz (eg. to 434.452)
• Press 'h' to open help dialog
• Press any key to close help dialog
• Bug: Original frequency is displayed (eg. 434.450), not tuned frequency.
• Press 'c'/'C' to tune downwards 1 KHz, this will be applied to the actual frequency, not the displayed frequency (eg. 434.451 is now shown)