Move the I2C speed config key out of the choice prompt.

Kconfig

@@ -12,14 +12,15 @@ menu "BMX280 Options"
             bool "I2C Master Driver (i2c_master.h)"
             help
                 Use I2C Master Driver (i2c_master.h) for ESP-IDF >= 5.3.
-        config BMX280_I2C_CLK_SPEED_HZ
-            int "I2C Clock Speed (Hz)"
-            default 100000
-            range 1000 400000
-            help
-                Set the I2C clock speed in Hz.
     endchoice
     
+    config BMX280_I2C_CLK_SPEED_HZ
+        int "I2C Clock Speed (Hz)"
+        default 100000
+        range 1000 400000
+        help
+            Set the I2C clock speed in Hz. Only applies to the new I2C Master driver.
+    
     choice BMX280_EXPECT_DEVICE
         prompt "Installed Sensor Model"
         help

bmx280.c

@@ -451,7 +451,7 @@ bmx280_t* bmx280_create_master(i2c_master_bus_handle_t bus_handle)
 void bmx280_close(bmx280_t *bmx280)
 {
     #if CONFIG_USE_I2C_MASTER_DRIVER
-    if(bmx280->i2c_dev!=NULL)
+    if(bmx280 != NULL && bmx280->i2c_dev != NULL)
         i2c_master_bus_rm_device(bmx280->i2c_dev);
     #endif
     free(bmx280);

include/bmx280_bits.h

@@ -126,7 +126,7 @@ typedef struct bmx280_config_t {
 #elif (CONFIG_BMX280_DEFAULT_STANDBY_10M)
 #define BMX280_DEFAULT_STANDBY BME280_STANDBY_10M
 #else
-#define BMX280_DEFAULT_STANDBY BMX280_STANDBY_20M
+#define BMX280_DEFAULT_STANDBY BME280_STANDBY_20M
 #endif
 
 #if (CONFIG_BMX280_DEFAULT_IIR_NONE)