mmc: sdhci-esdhc-imx: fix defined but not used warnings

Fix warnings when CONFIG_PM=y and CONFIG_PM_SLEEP is not set by
surrounding the 2 functions with #ifdef CONFIG_PM_SLEEP.

drivers/mmc/host/sdhci-esdhc-imx.c:1659:13: warning: 'sdhc_esdhc_tuning_restore' defined but not used [-Wunused-function]
 1659 | static void sdhc_esdhc_tuning_restore(struct sdhci_host *host)
drivers/mmc/host/sdhci-esdhc-imx.c:1637:13: warning: 'sdhc_esdhc_tuning_save' defined but not used [-Wunused-function]
 1637 | static void sdhc_esdhc_tuning_save(struct sdhci_host *host)

Fixes: 3d1eea493894 ("mmc: sdhci-esdhc-imx: Save tuning value when card stays powered in suspend")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Haibo Chen <haibo.chen@nxp.com>
Link: https://lore.kernel.org/r/20250424034610.441532-1-rdunlap@infradead.org


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>