mtd: rawnand: gpmi: add iMX8QXP support.

Add "fsl,imx8qxp-gpmi-nand" compatible string. iMX8QXP gpmi nand is similar
to iMX7D. But it is using 4 clocks: "gpmi_io", "gpmi_apb", "gpmi_bch" and
"gpmi_bch_apb".

Signed-off-by: Han Xu <han.xu@nxp.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20240520-gpmi_nand-v2-4-e3017e4c9da5@nxp.com