powerpc/8xx: add CONFIG_PIN_TLB_IMMR

CONFIG_PIN_TLB maps IMMR area and the first 24 Mbytes of memory.
In some circunstances it might be more interesting to not map
IMMR but map 32 Mbytes of memory instead.

Therefore we add config option CONFIG_PIN_TLB_IMMR to select if
IMMR shall be pinned or not, hence whether we pin 24 or 32 Mbytes of RAM

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 394f9dc..fcfe533 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -1056,6 +1056,11 @@
 config PIN_TLB
 	bool "Pinned Kernel TLBs (860 ONLY)"
 	depends on ADVANCED_OPTIONS && 8xx
+
+config PIN_TLB_IMMR
+	bool "Pinned TLB for IMMR"
+	depends on PIN_TLB
+	default y
 endmenu
 
 if PPC64