x86: Export kmap_atomic_prot() needed for TTM.

This functionality is needed to kmap_atomic() highmem pages that may
potentially have or are about to set up other mappings with
non-standard caching attributes.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

arch/x86/mm/highmem_32.c

@@ -103,6 +103,7 @@ EXPORT_SYMBOL(kmap);
 EXPORT_SYMBOL(kunmap);
 EXPORT_SYMBOL(kmap_atomic);
 EXPORT_SYMBOL(kunmap_atomic);
+EXPORT_SYMBOL(kmap_atomic_prot);
 
 void __init set_highmem_pages_init(void)
 {