drivers/st7735: fix inconsistency in dependency modeling

In KConfig `MODULE_ST7789` now is hidden module that automatically
gets selected when `HAVE_ST7789` is selected in `MODULE_ST7735` is used.

Co-authored-by: Gunar Schorcht <gunar@schorcht.net>

drivers/st7735/Kconfig

@@ -23,12 +23,15 @@ config HAVE_ST7735
       Indicates that an ST7735 display is present.
 
 config MODULE_ST7789
-    bool "ST7789 display driver"
-    select MODULE_ST7735
+    bool
+    depends on HAVE_ST7789
+    default y if MODULE_ST7735
+    help
+        ST7789 display driver
 
 config HAVE_ST7789
     bool
-    select MODULE_ST7789 if MODULE_DISP_DEV
+    select MODULE_ST7735 if MODULE_DISP_DEV
     help
       Indicates that an ST7789 display is present.