kernel/modules: Add missing config option

This configuration option was added in kernel 4.15 and is missing in the
kernel 4.19 configuration.

Fixes: ed2839ac419 ("kernel/modules: add kmod-pmbus-zl6100 module")
Signed-off-by: Hauke Mehrtens <[email protected]>

target/linux/generic/config-4.19

@@ -4320,6 +4320,7 @@ CONFIG_SELECT_MEMORY_MODEL=y
 # CONFIG_SENSORS_MAX197 is not set
 # CONFIG_SENSORS_MAX20751 is not set
 # CONFIG_SENSORS_MAX31722 is not set
+# CONFIG_SENSORS_MAX31785 is not set
 # CONFIG_SENSORS_MAX31790 is not set
 # CONFIG_SENSORS_MAX34440 is not set
 # CONFIG_SENSORS_MAX6621 is not set