spi: spi-nxp-fspi: set back to dll override mode when clock rate < 100MHz

JIRA: https://issues.redhat.com/browse/RHEL-104570

commit a9888b3
Author: Haibo Chen <haibo.chen@nxp.com>
Date:   Wed Sep 17 15:27:07 2025 +0800

    spi: spi-nxp-fspi: set back to dll override mode when clock rate < 100MHz

    Preparation of supportting DTR mode. In nor suspend, driver will disable
    DTR mode, and enable DTR mode back in nor resume. This require the flexspi
    driver has the ability to set back to dll override mode in STR mode when
    clock rate < 100MHz.

    Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
    Reviewed-by: Frank Li <Frank.Li@nxp.com>
    Link: https://patch.msgid.link/20250917-flexspi-ddr-v2-2-bb9fe2a01889@nxp.com
    Signed-off-by: Mark Brown <broonie@kernel.org>

Signed-off-by: Mattijs Korpershoek <mkorpershoek@redhat.com>

Author: makohoek

drivers/spi/spi-nxp-fspi.c

@@ -767,6 +767,8 @@ static void nxp_fspi_select_mem(struct nxp_fspi *f, struct spi_device *spi,
 	 */
 	if (rate > 100000000)
 		nxp_fspi_dll_calibration(f);
+	else
+		nxp_fspi_dll_override(f);
 
 	f->selected = spi_get_chipselect(spi, 0);
 }