The flexspi on imx8ulp only has 16 LUTs, different with others which
have up to 32 LUTs.

Add a separate compatible string and nxp_fspi_devtype_data to support
flexspi on imx8ulp.

Fixes: ef89fd56 ("arm64: dts: imx8ulp: add flexspi node")
Cc: stable@kernel.org
Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20240905094338.1986871-4-haibo.chen@nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>