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/drivers/of/Kconfig b/drivers/of/Kconfig
index d2fa27c..462825e 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -1,3 +1,7 @@
+config OF_FLATTREE
+	bool
+	depends on OF
+
 config OF_DEVICE
 	def_bool y
 	depends on OF && (SPARC || PPC_OF || MICROBLAZE)