riscv: define medeleg using CSR macros

[rmsyn]

Uses CSR helper macros to define the medeleg register.

Adds basic unit tests for the medeleg register.

Related: #229

[romancardenas]

Looks good to me!!

I understand that previously there were no setters in the Medeleg, right?

BTW: I like the approach of adding simple unit tests for these register proxies

[rmsyn]

I understand that previously there were no setters in the Medeleg, right?

Correct, there were no setters. I didn't know if this was intentional, because of the set_ and clear_ free functions.

medeleg is a read-write register from the spec, so I figured adding the setters was the way to go. Am I mistaken?

BTW: I like the approach of adding simple unit tests for these register proxies

❤️

[romancardenas]

Probably there weren't getter/setters because of the atomic set_* functions. However, with these new setters via a proxy, we can modify the medeleg CSR with just one write to the actual register.