Macro write_csr

macro_rules! write_csr {
    ($csr_number:literal) => { ... };
    ($csr_number:literal, $($cfg:meta),*) => { ... };
}

Convenience macro to wrap the csrrw assembly instruction for writing to CSR registers.

This macro should generally not be called directly.

Instead, use the write_csr_as_usize macro.