refactor(kernel): un-ignore the clippy::inconsistent_digit_grouping lint in ctz3_lut_nonzero

It's no longer reported for an integer literal
`0b01_00_10_00_01_00_0000_0000_0000_0000`.

Author: yvt

src/r3_kernel/src/utils/ctz.rs

@@ -173,7 +173,6 @@ fn ctz3_lut(x: usize) -> u32 {
 #[inline]
 // This code groups digits irregularly to express a specific meaning
 #[expect(clippy::unusual_byte_groupings)]
-#[allow(clippy::inconsistent_digit_grouping)]
 fn ctz3_lut_nonzero(x: usize) -> u32 {
     debug_assert!(x < 8);
     debug_assert!(x != 0);