Add support of AT32F435/437 that includes gpio、bus and clock.

[qff233]

1. add bus of at32f435/437
2. add gpio of at32f435/437
3. add clock of at32f435/437

[qff233]

Add buses, clocks, and peripherals according to the official register manual. One of this is shown in the image above.

[kossnikita]

I'm sorry for the delay. I haven't been feeling well these days.
As I mentioned before in #3 (comment), we need to implement F3-like GPIO first, before this pins implementation.
The fields in CRM do not relate to a specific controller, but to many of them, so you need to configure this not only for the F415 or F435. You can check this in the register comparison table (see #3 (comment)).
I'll take care of the GPIO implementation when I go back to work (in a week or so)