dt-bindings: serial: fsl-lpuart: Remove i.MX8QM from enum

dt-bindings: serial: fsl-lpuart: Remove i.MX8QM from enum

i.MX8QM lpuart is backwards compatible with i.MX8QXP, so lets remove
the single match from enum. This will force nodes to have both compatible
strings, since there is already an 'items' entry for that.

Reviewed-by: Peng Fan <peng.fan@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Link: https://lore.kernel.org/r/20220210201407.567860-2-abel.vesa@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>