target/alpha: Replace VMSTATE_UINTTL() -> VMSTATE_UINT64()

target/alpha: Replace VMSTATE_UINTTL() -> VMSTATE_UINT64()

All these CPUAlphaState fields are of uint64_t type (except
the @fir[] array which uses float64, expanded to the same
type definition). Use the appropriate VMSTATE_UINT64() macro.

There is no functional change (the migration stream is not
modified), because the Alpha targets are only built as 64-bit:

  $ git grep TARGET_LONG_BITS configs/targets/alpha*
  configs/targets/alpha-linux-user.mak:4:TARGET_LONG_BITS=64
  configs/targets/alpha-softmmu.mak:2:TARGET_LONG_BITS=64

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Anton Johansson <anjo@rev.ng>
Message-Id: <20250925005137.59378-1-philmd@linaro.org>