Patch to use RetroArch v1.9.0 on Enigma2 box.

retroarch_on_enigma2.diff

# Fix for run RetroArch v1.9.0 released version on Atto Enigma2 box.
#
# Compile example:
# CFLAGS="-march=armv7ve -mtune=cortex-a53 -mfpu=neon-vfpv4 -mvectorize-with-neon-quad" ./configure --prefix=/usr --enable-xmb --enable-libusb --enable-alsa --enable-egl --disable-opengl1 --enable-opengles --enable-opengles3 --enable-mali_fbdev --enable-threads --enable-thread_storage --enable-ffmpeg --disable-cdrom --disable-x11 --disable-pulse --disable-oss --disable-qt --disable-sdl --disable-sdl2 --disable-wayland
# make HAVE_NEON=1

diff --git a/input/drivers/udev_input.c b/input/drivers/udev_input.c
index 0dd54091d3..549445f383 100644
--- a/input/drivers/udev_input.c
+++ b/input/drivers/udev_input.c
@@ -162,10 +162,21 @@ static unsigned input_unify_ev_key_code(unsigned code)
       so unify remote control keysyms to keyboard keysyms here.  */
    switch (code)
    {
+      case KEY_BACK:
+      case KEY_EXIT:
+          return KEY_BACKSPACE;
+      case KEY_MENU:
+         return KEY_F1;
+      case KEY_MUTE:
+         return KEY_F9;
       case KEY_OK:
          return KEY_ENTER;
-      case KEY_BACK:
-         return KEY_BACKSPACE;
+      case KEY_POWER:
+         return KEY_ESC;
+      case KEY_VOLUMEDOWN:
+         return KEY_KPMINUS;
+      case KEY_VOLUMEUP:
+         return KEY_KPPLUS;
       default:
          return code;
    }