drivers/mpu9x50: Model saul_default in kconfig

drivers/mpu9x50/Kconfig

@@ -5,30 +5,46 @@
 # directory for more details.
 #
 
-if TEST_KCONFIG
 
-choice
-    bool "MPU-9X50 accelerometer/magnetometer/gyroscope"
-    optional
-    depends on HAS_PERIPH_I2C
-    help
-        This driver supports both MPU9150 and MPU9250. Choose one model.
-
-config MODULE_MPU9150
-    bool "MPU-9150"
-    select MODULE_MPU9X50
-
-config MODULE_MPU9250
-    bool "MPU-9250"
-    select MODULE_MPU9X50
-
-endchoice
-
-config MODULE_MPU9X50
+menuconfig MODULE_MPU9X50
     bool
+    prompt "MPU-9X50 accelerometer/magnetometer/gyroscope" if !(MODULE_SAUL_DEFAULT && HAVE_MPU9X50)
+    default y if (MODULE_SAUL_DEFAULT && HAVE_MPU9X50)
+    depends on TEST_KCONFIG
     depends on HAS_PERIPH_I2C
     select MODULE_PERIPH_I2C
     select MODULE_ZTIMER
     select MODULE_ZTIMER_MSEC
 
-endif # TEST_KCONFIG
+choice
+    bool "Sensor variant"
+    default MODULE_MPU9150 if HAVE_MPU9150
+    default MODULE_MPU9250 if HAVE_MPU9250
+    depends on MODULE_MPU9X50
+    help
+        This driver supports both MPU9150 and MPU9250. Choose one model.
+
+config MODULE_MPU9150
+    bool "MPU-9150"
+
+config MODULE_MPU9250
+    bool "MPU-9250"
+
+endchoice
+
+config HAVE_MPU9150
+    bool
+    select HAVE_MPU9X50
+    help
+      Indicates that a mpu9150 sensor is present.
+
+config HAVE_MPU9250
+    bool
+    select HAVE_MPU9X50
+    help
+      Indicates that a mpu9250 sensor is present.
+
+config HAVE_MPU9X50
+    bool
+    help
+      Indicates that a mpu9X50 sensor is present.

tests/driver_mpu9x50/app.config.test

@@ -1,5 +1,5 @@
 # this file enables modules defined in Kconfig. Do not use this file for
 # application configuration. This is only needed during migration.
-CONFIG_MODULE_MPU9150=y
+CONFIG_MODULE_MPU9X50=y
 CONFIG_MODULE_ZTIMER=y
 CONFIG_MODULE_ZTIMER_MSEC=y