microblaze: Improve TLB calculation for small systems

Systems with small amount of memory need to be handled
differently. Linux can't allocate the whole 32MB with two TLBs
because then there is no MMU protection.

Signed-off-by: Michal Simek <monstr@monstr.eu>
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index 86ae278..d64c100 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -259,6 +259,10 @@
 
 endchoice
 
+config KERNEL_PAD
+	hex "Kernel PAD for unpacking" if ADVANCED_OPTIONS
+	default "0x80000" if MMU
+
 endmenu
 
 source "mm/Kconfig"