dt-bindings: lpspi: Document support for S32G

dt-bindings: lpspi: Document support for S32G

Add compatible strings 'nxp,s32g2-lpspi' and 'nxp,s32g3-lpspi' for S32G2
and S32G3. Require nxp,s32g3-lpspi to fallback to nxp,s32g2-lpspi since
they are currently compatible.

Signed-off-by: Larisa Grigore <larisa.grigore@nxp.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20250828-james-nxp-lpspi-v2-5-6262b9aa9be4@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>