PPC: remove dead boards (AMX860, c2mon, ETX094, IAD210, LANTEC, SCM)

These boards have long reached EOL, and there has been no indication
of any active users of such hardware for years.  Get rid of the dead
weight.

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Wolfgang Grandegger <wg@denx.de>
diff --git a/README b/README
index 69da2b8..4f16240 100644
--- a/README
+++ b/README
@@ -2182,8 +2182,8 @@
 		following board configurations are known to be
 		"pRAM-clean":
 
-			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
-			HERMES, IP860, RPXlite, LWMON, LANTEC,
+			IVMS8, IVML24, SPD8xx, TQM8xxL,
+			HERMES, IP860, RPXlite, LWMON,
 			FLAGADM, TQM8260
 
 - Error Recovery: