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/MPC8641HPCN.h b/include/configs/MPC8641HPCN.h
index 9acc3da..49ee7ff 100644
--- a/include/configs/MPC8641HPCN.h
+++ b/include/configs/MPC8641HPCN.h
@@ -67,6 +67,7 @@
 #define BANK_INTERLEAVING		0x22000000
 #define SUPER_BANK_INTERLEAVING		0x23000000
 
+#define CONFIG_HIGH_BATS	1	/* High BATs supported and enabled */
 
 #define CONFIG_ALTIVEC		1