lvgl: remove useless FILES include

As ${includedir}${PN} is already listed in FILES, there is no
need to add one of its subdirectories.

Signed-off-by: Christophe Chapuis <chris.chapuis@gmail.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-graphics/lvgl/lvgl_9.0.0.bb

@@ -34,5 +34,4 @@ do_install:append() {
 
 FILES:${PN}-dev += "\
     ${includedir}/${PN}/ \
-    ${includedir}/${PN}/lvgl/ \
     "