serial: remove uneeded type conversions
serial: remove uneeded type conversions

We were doing some uneeded type conversion from u64 to u64.
This was probably leftover code from a different refactoring.

Signed-off-by: Andreea Florescu <f68a7d732e796861f8e79ea704b43a5ee52eddaf@amazon.com>

firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker