arch: drop BR2_BINFMT_FLAT_SEP_DATA support

This was only used by Blackfin, so there's no good reason to keep it.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
diff --git a/Config.in.legacy b/Config.in.legacy
index 3d20950..eeefea1 100644
--- a/Config.in.legacy
+++ b/Config.in.legacy
@@ -162,6 +162,13 @@
 	  See https://sourceforge.net/p/e1000/bugs/589/ for the
 	  discussion.
 
+config BR2_BINFMT_FLAT_SEP_DATA
+	bool "binfmt FLAT with separate code and data removed"
+	select BR2_LEGACY
+	help
+	  This FLAT binary format was only used on Blackfin, which has
+	  been removed.
+
 config BR2_bfin
 	bool "Blackfin architecture support removed"
 	select BR2_LEGACY