serial: core: Fix iotype userspace breakage

serial: core: Fix iotype userspace breakage

commit 3ffb1a8193bea ("serial: core: Add big-endian iotype")
re-numbered userspace-dependent values; ioctl(TIOCSSERIAL) can
assign the port iotype (which is expected to match the selected
i/o accessors), so iotype values must not be changed.

Cc: Kevin Cernekee <[email protected]>
Cc: <[email protected]> # 3.19+
Signed-off-by: Peter Hurley <[email protected]>
Reviewed-by: Kevin Cernekee <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>