x86_64: Quieten Atari keyboard warnings in Kconfig

Not directly related to x86, but I got tired of seeing these warnings on every
kconfig update when building on a non m68k box:

drivers/input/keyboard/Kconfig:170:warning: 'select' used by config symbol 'KEYBOARD_ATARI' refers to undefined symbol 'ATARI_KBD_CORE'
drivers/input/mouse/Kconfig:182:warning: 'select' used by config symbol 'MOUSE_ATARI' refers to undefined symbol 'ATARI_KBD_CORE'

I moved the definition of ATARI_KBD_CORE into drivers/input/keyboard/Kconfig
so it's always seen by Kconfig.

Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
index bd707b8..c97d5eb 100644
--- a/drivers/input/keyboard/Kconfig
+++ b/drivers/input/keyboard/Kconfig
@@ -164,6 +164,9 @@
 	  To compile this driver as a module, choose M here: the
 	  module will be called amikbd.
 
+config ATARI_KBD_CORE
+	bool
+
 config KEYBOARD_ATARI
 	tristate "Atari keyboard"
 	depends on ATARI