of/flattree: merge find_flat_dt_string and initial_boot_params

Merge common code between Microblaze and PowerPC.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Reviewed-by: Wolfram Sang <w.sang@pengutronix.de>
Tested-by: Michal Simek <monstr@monstr.eu>
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 2ba14e7..2a75c6ae 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -163,6 +163,7 @@
 
 config OF
 	def_bool y
+	select OF_FLATTREE
 
 config PPC_UDBG_16550
 	bool