Add Mayflash N64 Controller Adapter mapping for SDL2

[ExtremelyLazyCat]

• I confirm that I am the author of this code and release it to the SDL project under the Zlib license. This contribution does not contain code from other sources, including code generated by a Large Language Model ("AI").

This commit adds support for the Mayflash USB N64 Controller Adapter for the SDL2 branch.

Description

A previous PR by @JunielKatarn was reverted as there is a conflicting GUID with the "HuiJia SNES Controller"; this mapping includes a CRC identifier to avoid conflicts. I'm pulling this to the SDL2 branch as my main motivation was to fix support on BizHawk which uses SDL2 but I can also open a separate PR on main if desired.

Existing Issue(s)

#6079
TASEmulators/BizHawk#4280

[slouken]

Yes, please provide a PR against main, and I'll merge them both. Thanks!