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/mpc5121ads.h b/include/configs/mpc5121ads.h
index 07e7747..f5c2bd3 100644
--- a/include/configs/mpc5121ads.h
+++ b/include/configs/mpc5121ads.h
@@ -48,6 +48,8 @@
 #define CONFIG_MPC512X		1	/* MPC512X family */
 #define CONFIG_FSL_DIU_FB	1	/* FSL DIU */
 
+#define	CONFIG_SYS_TEXT_BASE	0xFFF00000
+
 /* video */
 #undef CONFIG_VIDEO