Blackfin: SMP: add flush_tlb_kernel_range stub

Newer code in mm/page_alloc.c requires this function now in arches.
Signed-off-by: NGraf Yang <graf.yang@analog.com>
Signed-off-by: NMike Frysinger <vapier@gentoo.org>

arch/blackfin/include/asm/tlbflush.h

 #include <asm-generic/tlbflush.h>
+#define flush_tlb_kernel_range(s, e) do { } while (0)