serial: imx: Simplify compatibility handling

serial: imx: Simplify compatibility handling

Three of the four entries of imx_uart_devdata[] use .uts_reg =
IMX21_UTS. The difference in the .devtype member isn't relevant, the
only thing that matters is if is equal to IMX1_UART.

So use an entry with .devtype = IMX21_UART on all platforms but i.MX1.
There is no need to have the dev types in an array, so split them up in
two separate variables.

The fsl,imx53-uart devinfo can go away because in the binding and also
the dts files all fsl,imx53-uart devices also are compatible to
fsl,imx21-uart. That's not the case for fsl,imx6q-uart (which is a bit
strange IMHO), so the fsl,imx6q-uart must stay around.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230911085451.628798-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>