fixup: riscv: remove equality check in CSR macros

Removes the equality check for range branches in CSR helper macros.

Users who want a single-bit field, i.e. `start == end`, should use the
single-bit branch variants.

Authored-by: rmsyn <[email protected]>
Co-authored-by: romancardenas <[email protected]>

Author: rmsyn

riscv/src/register/macros.rs

@@ -881,7 +881,7 @@ macro_rules! read_only_csr_field {
      $try_field:ident,
      range: $bit_start:literal..=$bit_end:literal$(,)?) => {
         const _: () = assert!($bit_end < usize::BITS);
-        const _: () = assert!($bit_start <= $bit_end);
+        const _: () = assert!($bit_start < $bit_end);
 
         impl $ty {
             $(#[$field_doc])+
@@ -910,7 +910,7 @@ macro_rules! read_only_csr_field {
      $(#[$field_doc:meta])+
      $field:ident: [$bit_start:literal : $bit_end:literal]$(,)?) => {
         const _: () = assert!($bit_end < usize::BITS);
-        const _: () = assert!($bit_start <= $bit_end);
+        const _: () = assert!($bit_start < $bit_end);
 
         impl $ty {
             $(#[$field_doc])+
@@ -1010,7 +1010,7 @@ macro_rules! write_only_csr_field {
      $try_field:ident,
      range: $bit_start:literal..=$bit_end:literal$(,)?) => {
         const _: () = assert!($bit_end < usize::BITS);
-        const _: () = assert!($bit_start <= $bit_end);
+        const _: () = assert!($bit_start < $bit_end);
 
         impl $ty {
             $(#[$field_doc])+
@@ -1040,7 +1040,7 @@ macro_rules! write_only_csr_field {
      $(#[$field_doc:meta])+
      $field:ident: [$bit_start:literal : $bit_end:literal]$(,)?) => {
         const _: () = assert!($bit_end < usize::BITS);
-        const _: () = assert!($bit_start <= $bit_end);
+        const _: () = assert!($bit_start < $bit_end);
 
         impl $ty {
             $(#[$field_doc])+