mtd: nand: raw: gpmi: improve power management handling

Refactor the power management handling in the gpmi nand driver. Remove
redundant pm_runtime calls in the driver probe function. Handle the pad
control and use the leverage runtime suspend and resume calls to take
care of clocks in system suspend and resume functions.

Signed-off-by: Han Xu <han.xu@nxp.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20241007191319.220775-2-han.xu@nxp.com