lvgl: install lv_conf.h in ${includedir}/${BPN}

* with multilib lib32-lvgl installs all headers except lv_conf.h into:
  ${includedir}/lvgl only lv_conf.h ends in ${includedir}/lib32-lvgl/
  which is wrong and not included in any includepaths:

  $ cat lib32-lvgl/9.1.0/image/usr/lib32/pkgconfig/lvgl.pc
  prefix="/usr"
  includedir="${prefix}/include/lvgl"
  libdir=${prefix}/lib

  Name: lvgl
  Description: Light and Versatile Graphics Library
  URL: https://lvgl.io/
  Version: 9.1.0
  Cflags: -I${includedir}
  Libs: -L${libdir} -llvgl

Signed-off-by: Martin Jansa <martin.jansa@gmail.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-graphics/lvgl/lvgl_9.1.0.bb

@@ -24,10 +24,5 @@ S = "${WORKDIR}/git"
 require lv-conf.inc
 
 do_install:append() {
-    install -d "${D}${includedir}/${PN}"
-    install -m 0644 "${S}/lv_conf.h" "${D}${includedir}/${PN}/lv_conf.h"
+    install -m 0644 "${S}/lv_conf.h" "${D}${includedir}/${BPN}/lv_conf.h"
 }
-
-FILES:${PN}-dev += "\
-    ${includedir}/${PN}/ \
-    "