[Bug target/113856] `(vect64 float){1.0f, 0}` code generation could just be `fmov sN, 1.0f`

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113856

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note for:
```
#define vect128 __attribute__((vector_size(16) ))

vect128  float f1()
{
  return (vect64 float){1.0f, 1.0f, 0.0f, 0.0f};
}
```

Should also be able to do:
```
fmov v0.2s, 1.0
```

The instruction here does zero the upper parts of the register too.
I have a patch for that too.