fam_wrappers: Remove code snippet of kvm_save2.len

Code snippet for len field of kvm_xsave2 is outdate for a long while,
which also fails to compile. Change the code snippet to pseudo code.

Signed-off-by: Ruoqing He <[email protected]>

Author: RuoqingHe

kvm-bindings/src/x86_64/fam_wrappers.rs

@@ -134,10 +134,8 @@ pub struct kvm_xsave2 {
     ///
     /// Note that `KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2)` returns the size of the entire
     /// `kvm_xsave` structure, e.g. the sum of header and FAM. Thus, this `len` field
-    /// is equal to
-    /// ```norun
-    /// (KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2) - sizeof::<kvm_xsave>()).div_ceil(sizeof::<__u32>())
-    /// ```
+    /// is equal to `KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2)`, which should also be equal
+    /// to `sizeof::<kvm_xsave>()).div_ceil(sizeof::<__u32>())`.
     pub len: usize,
     pub xsave: kvm_xsave,
 }