rust/vmstate: Fix unnecessary VMState bound of with_varray_flag()

The VMState type bound is not used in with_varray_flag().

And for vmstate_struct, Rust cannot infer the type of `num` from the
call_func_with_field(), so this causes the compiling error because it
complains "cannot satisfy `_: VMState`" in with_varray_flag().

Note Rust can infer the type in vmstate_of macro so that
with_varray_flag() can work at there. It is possible that the different
initialization ways in the two macros cause differences in Rust's
type inference.

But in fact, the VMState type bound is not used in with_varray_flag()
and vmstate_varray_flag() has already checked the VMState type, it's
safe to drop VMState bound of with_varray_flag(), which can fix the
above compiling error.

Signed-off-by: Zhao Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Paolo Bonzini <[email protected]>

Author: trueptolemy

rust/qemu-api/src/vmstate.rs

@@ -275,7 +275,7 @@ impl VMStateField {
     }
 
     #[must_use]
-    pub const fn with_varray_flag<T: VMState>(mut self, flag: VMStateFlags) -> VMStateField {
+    pub const fn with_varray_flag(mut self, flag: VMStateFlags) -> VMStateField {
         assert!((self.flags.0 & VMStateFlags::VMS_ARRAY.0) != 0);
         self.flags = VMStateFlags(self.flags.0 & !VMStateFlags::VMS_ARRAY.0);
         self.flags = VMStateFlags(self.flags.0 | flag.0);