serial: s5p: Add Apple M1 support

Apple M1 SoCs include an S5L UART which is a variant of the S5P
UART.  Add support for this variant and enable it by default
on Apple SoCs.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
5 files changed