register: add dcsr CSR support

Author: KushalMeghani1644

riscv/src/register.rs

@@ -125,4 +125,5 @@ mod tests;
 
 // TODO: Debug/Trace Registers (shared with Debug Mode)
 
-// TODO: Debug Mode Registers
+// Debug Mode Registers
+pub mod dcsr;

riscv/src/register/dcsr.rs

@@ -0,0 +1,4 @@
+//! dcsr register — Debug Control and Status Register (0x7b0)
+
+read_csr_as_usize!(0x7b0);
+write_csr_as_usize!(0x7b0);