[POWERPC] Remove flush_dcache_all export

Removes the flush_dcache_all export for non coherent platforms.
We removed the last in-kernel user of this years ago in arch/ppc
so it no longer serves a purpose. Plus, it breaks the build
at the moment.
Signed-off-by: NMatt Porter <mporter@embeddedalley.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

arch/powerpc/kernel/ppc_ksyms.c

@@ -126,10 +126,6 @@ EXPORT_SYMBOL(pci_bus_mem_base_phys);
 EXPORT_SYMBOL(pci_bus_to_hose);
 #endif /* CONFIG_PCI */
 
-#ifdef CONFIG_NOT_COHERENT_CACHE
-EXPORT_SYMBOL(flush_dcache_all);
-#endif
-
 EXPORT_SYMBOL(start_thread);
 EXPORT_SYMBOL(kernel_thread);