mtd: nand: raw: gpmi: fix clocks when CONFIG_PM=N

Commit f04ced6d ("mtd: nand: raw: gpmi: improve power management
handling") moved all clock handling into PM callbacks. With CONFIG_PM
disabled, those callbacks are missing, leaving the driver unusable.

Add clock init/teardown for !CONFIG_PM builds to restore basic operation.
Keeping the driver working without requiring CONFIG_PM is preferred over
adding a Kconfig dependency.

Fixes: f04ced6d ("mtd: nand: raw: gpmi: improve power management handling")
Signed-off-by: Maarten Zanders <maarten@zanders.be>
Cc: stable@vger.kernel.org
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>