Input: add support for Braille devices

- Add KEY_BRL_* input keys and K_BRL_* keycodes;
- Add emulation of how braille keyboards usually combine braille dots
  to the console keyboard driver;
- Add handling of unicode U+28xy diacritics.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/include/linux/kbd_kern.h b/include/linux/kbd_kern.h
index e87c32a..4eb851e 100644
--- a/include/linux/kbd_kern.h
+++ b/include/linux/kbd_kern.h
@@ -135,6 +135,8 @@
 
 #define U(x) ((x) ^ 0xf000)
 
+#define BRL_UC_ROW 0x2800
+
 /* keyboard.c */
 
 struct console;