At present, the serial drivers qemu_serial.c and serial_pl011.c on the fvp-v8r and qemu platforms in arm64 are duplicated
and need to be merged. The plan is to place them under the drivers\serial directory to create a common code module,
so that both fvp-v8r and qemu can use the same code.
In the future, if new platforms use pl011 serial ports, they can also be directly reused
Signed-off-by: hujun5 <hujun5@xiaomi.com>