Remove redundant intra-doc link definitions in _mm_clflushopt

rustdoc resolves _mm_clflush/_mm_sfence/_mm_mfence automatically as
intra-doc links since they are in scope under core::arch::x86_64; the
explicit reference-definition lines were unnecessary. Other intrinsics
(avx.rs, avx512f.rs) already link these bare in prose without definitions.

Author: jlpetz

crates/core_arch/src/x86/clflushopt.rs

@@ -26,10 +26,6 @@ unsafe extern "C" {
 /// Unlike the prefetch intrinsics, `CLFLUSHOPT` is subject to all the
 /// permission checking and faults associated with a byte load, so `p` must
 /// point to a byte that is valid for reads.
-///
-/// [`_mm_clflush`]: crate::arch::x86_64::_mm_clflush
-/// [`_mm_sfence`]: crate::arch::x86_64::_mm_sfence
-/// [`_mm_mfence`]: crate::arch::x86_64::_mm_mfence
 #[inline]
 #[target_feature(enable = "clflushopt")]
 #[cfg_attr(test, assert_instr(clflushopt))]