Makefile: move all Power Architecture boards into boards.cfg

Clean up Makefile, and drop a lot of the config.mk files on the way.

We now also automatically pick all boards that are listed in
boards.cfg (and with all configurations), so we can drop the redundant
entries from MAKEALL to avoid building these twice.

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/include/configs/t3corp.h b/include/configs/t3corp.h
index 39ca793..d00e64e 100644
--- a/include/configs/t3corp.h
+++ b/include/configs/t3corp.h
@@ -31,6 +31,10 @@
 #define CONFIG_440		1
 #define CONFIG_4xx		1	/* ... PPC4xx family */
 
+#ifndef CONFIG_SYS_TEXT_BASE
+#define CONFIG_SYS_TEXT_BASE	0xFFFA0000
+#endif
+
 #define CONFIG_HOSTNAME		t3corp
 
 /*