noise channel emulation is kinda off

[djmaximum17]

lower frequency registers of the noise channel seem to be incorrect. VBA-M and other GB emulators get it right.

https://user-images.githubusercontent.com/61179162/106647240-4c7f4700-6554-11eb-9dfb-bd4de24a2a6b.mov

https://user-images.githubusercontent.com/61179162/106647278-57d27280-6554-11eb-8b80-98e1aeecdfea.mov

[jkotlinski]

It appears that @djmaximum17 uses a CGB-A for comparison.

[LIJI32]

I need a test ROM to test it on various hardware revisions and the latest master.

[Nimta]

I've also noticed a tiny bit of extra popping while playing on the Retroarch core version. It seems to pop whenever the noise channel's note is halted.