serial: amba-pl011: move header content to .c

There is no point keeping the header content separated. In this case, it
is only an enum. So move the enum to the appropriate source file.

Cc: Russell King <linux@armlinux.org.uk>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220519075720.31402-1-jslaby@suse.cz


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>