acpi: remove final __acpi_map_table mapping before setting acpi_gbl_permanent_mmap

On x86, __acpi_map_table uses early_ioremap() to create the mapping,
replacing the previous mapping with a new one.  Once enough of the
kernel is up an running it switches to using normal ioremap().  At
that point, we need to clean up the final mapping to avoid a warning
from the early_ioremap subsystem.

This can be removed after all the instances in the ACPI code are fixed
that rely on early-ioremap's implicit overmapping of previously
mapped tables.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Len Brown <len.brown@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 5424a18..7217834 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -124,12 +124,14 @@
 	static char *prev_map;
 	static unsigned long prev_size;
 
+	if (prev_map) {
+		early_iounmap(prev_map, prev_size);
+		prev_map = NULL;
+	}
+
 	if (!phys || !size)
 		return NULL;
 
-	if (prev_map)
-		early_iounmap(prev_map, prev_size);
-
 	prev_size = size;
 	prev_map = early_ioremap(phys, size);