regulator: Fix MFD_MAX597X dependency

Drivers should depend on rather than select their MFDs.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220707111753.16581-1-broonie@kernel.orgSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/Kconfig

@@ -550,7 +550,7 @@ config REGULATOR_MAX597X
 	tristate "Maxim 597x power switch and monitor"
 	depends on I2C
 	depends on OF
-	select MFD_MAX597X
+	depends on MFD_MAX597X
 	help
 	  This driver controls a Maxim 5970/5978 switch via I2C bus.
 	  The MAX5970/5978 is a smart switch with no output regulation, but