powerpc: Export memstart_addr and kernstart_addr on ppc64

Some modules (like eHCA) want to map all of kernel memory, for this to
work with a relocated kernel, we need to export kernstart_addr so
modules can use PHYSICAL_START and memstart_addr so they could use
MEMORY_START.  Note that the 32bit code already exports these symbols.
Signed-off-By: Sonny Rao <sonnyrao@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/mm/init_64.c

@@ -79,7 +79,9 @@
 #endif /* CONFIG_PPC_STD_MMU_64 */
 
 phys_addr_t memstart_addr = ~0;
+EXPORT_SYMBOL_GPL(memstart_addr);
 phys_addr_t kernstart_addr;
+EXPORT_SYMBOL_GPL(kernstart_addr);
 
 void free_initmem(void)
 {