ahci: imx: fix building without hwmon or thermal

When CONFIG_HWMON is disabled, we now get a link failure:

ERROR: "devm_hwmon_device_register_with_groups" [drivers/ata/ahci_imx.ko] undefined!
drivers/ata/ahci_imx.o: In function `imx_ahci_probe':
ahci_imx.c:(.text.imx_ahci_probe+0x304): undefined reference to `devm_thermal_zone_of_sensor_register'

This makes the code calling into the hwmon subsystem compile-time
conditional, and adds a Kconfig dependency to avoid the corner
case of having HWMON=m and AHCI_IMX=y, by forcing AHCI_IMX=m in this
case. The thermal subsystem already has a check in its header, but
that also doesn't cover the THERMAL=m case, so we need a somewhat
complex Kconfig expression to handle all cases.

Fixes: 54643a8 ("ahci: imx: Add imx53 SATA temperature sensor support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

drivers/ata/Kconfig

@@ -129,6 +129,7 @@ config AHCI_ST
 config AHCI_IMX
 	tristate "Freescale i.MX AHCI SATA support"
 	depends on MFD_SYSCON && (ARCH_MXC || COMPILE_TEST)
+	depends on (HWMON && (THERMAL || !THERMAL_OF)) || !HWMON
 	help
 	  This option enables support for the Freescale i.MX SoC's
 	  onboard AHCI SATA.

drivers/ata/ahci_imx.c

@@ -774,7 +774,8 @@ static int imx_ahci_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	if (imxpriv->type == AHCI_IMX53) {
+	if (imxpriv->type == AHCI_IMX53 &&
+	    IS_ENABLED(CONFIG_HWMON)) {
 		/* Add the temperature monitor */
 		struct device *hwmon_dev;