x86: OLPC: Remove extra OLPC_OPENFIRMWARE_DT indirection

OLPC_OPENFIRMWARE_DT is just there to be selected by OLPC and selects
OF_PROMTREE. So let OLPC select OF_PROMTREE and remove that extra
config indirection. Fixup code and Makefile and use CONFIG_OF_PROMTREE
instead.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andres Salomon <dilinger@queued.net>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 677501d..4f3d3d4 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2069,7 +2069,7 @@
 	depends on !X86_PAE
 	select GPIOLIB
 	select OF
-	select OLPC_OPENFIRMWARE_DT if PROC_DEVICETREE
+	select OF_PROMTREE if PROC_DEVICETREE
 	---help---
 	  Add support for detecting the unique features of the OLPC
 	  XO hardware.
@@ -2080,10 +2080,6 @@
 	---help---
 	  Add support for non-essential features of the OLPC XO-1 laptop.
 
-config OLPC_OPENFIRMWARE_DT
-	bool
-	select OF_PROMTREE
-
 endif # X86_32
 
 config AMD_NB