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/spc1920.h b/include/configs/spc1920.h
index f81165b..75ed618 100644
--- a/include/configs/spc1920.h
+++ b/include/configs/spc1920.h
@@ -26,6 +26,8 @@
 #define CONFIG_SPC1920			1	/* SPC1920 board */
 #define CONFIG_MPC885			1	/* MPC885 CPU */
 
+#define	CONFIG_SYS_TEXT_BASE	0xFFF00000
+
 #define	CONFIG_8xx_CONS_SMC1		/* Console is on SMC1 */
 #undef	CONFIG_8xx_CONS_SMC2
 #undef	CONFIG_8xx_CONS_NONE