serial: Rename uart_change_speed() to uart_change_line_settings()

uart_change_speed() changes more than just speed so rename it to more
generic uart_change_line_settings().

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230309080923.11778-6-ilpo.jarvinen@linux.intel.com


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