chore(doc-build warnings): struct adjustments to work around Breathe bug

src/draw/nxp/pxp/lv_draw_pxp.h

@@ -36,7 +36,7 @@ extern "C" {
  *      TYPEDEFS
  **********************/
 
-typedef struct lv_draw_pxp_unit_t {
+typedef struct _lv_draw_pxp_unit_t {
     lv_draw_unit_t base_unit;
     lv_draw_task_t * task_act;
 #if LV_USE_OS

src/others/monkey/lv_monkey.h

@@ -27,21 +27,25 @@ extern "C" {
 
 typedef struct _lv_monkey_t lv_monkey_t;
 
+typedef struct {
+    int32_t min;
+    int32_t max;
+} lv_range_t;
+
+typedef struct {
+    uint32_t min;
+    uint32_t max;
+} lv_urange_t;
+
 struct _lv_monkey_config_t {
     /** Input device type */
     lv_indev_type_t type;
 
     /** Monkey execution period */
-    struct {
-        uint32_t min;
-        uint32_t max;
-    } period_range;
+    lv_urange_t period_range;
 
     /** The range of input value */
-    struct {
-        int32_t min;
-        int32_t max;
-    } input_range;
+    lv_range_t input_range;
 };
 
 /**********************