PPC: Create and use CONFIG_HIGH_BATS

Change all code that conditionally operates on high bat
registers (that is, BATs 4-7) to look at CONFIG_HIGH_BATS
instead of the myriad ways this is done now.  Define the option
for every config for which high bats are supported (and
enabled by early boot, on parts where they're not always
enabled)

Signed-off-by: Becky Bruce <becky.bruce@freescale.com>
diff --git a/include/configs/aev.h b/include/configs/aev.h
index e3f810c..c5e4759 100644
--- a/include/configs/aev.h
+++ b/include/configs/aev.h
@@ -41,6 +41,8 @@
 #define CONFIG_AEVFIFO		1
 #define CFG_MPC5XXX_CLKIN	33000000 /* ... running at 33.000000MHz */
 
+#define CONFIG_HIGH_BATS	1	/* High BATs supported */
+
 #define BOOTFLAG_COLD		0x01	/* Normal Power-On: Boot from FLASH  */
 #define BOOTFLAG_WARM		0x02	/* Software reboot	     */