core: pv - use active values for pv buffer slots and size

- during startup, param value and active can be different, up to the
moment when the config is completely loaded

(cherry picked from commit a156c62)
(cherry picked from commit 3929986)
(cherry picked from commit 2ad024f)

pvapi.c

@@ -2034,7 +2034,8 @@ char* pv_get_buffer(void)
 	char *p;
 
 	p = _pv_print_buffer[_pv_print_buffer_index];
-	_pv_print_buffer_index = (_pv_print_buffer_index+1)%_pv_print_buffer_slots;
+	_pv_print_buffer_index = (_pv_print_buffer_index+1)
+			% _pv_print_buffer_slots_active;
 
 	return p;
 }
@@ -2044,15 +2045,15 @@ char* pv_get_buffer(void)
  */
 int pv_get_buffer_size(void)
 {
-	return _pv_print_buffer_size;
+	return _pv_print_buffer_size_active;
 }
 
 /**
  *
  */
 int pv_get_buffer_slots(void)
 {
-	return _pv_print_buffer_slots;
+	return _pv_print_buffer_slots_active;
 }
 
 /**