Blackfin: fix bug found by traps test case 21

The traps test case 21 "exception 0x3f: l1_instruction_access" would make
the kernel panic on BF533's because we end up calling show_stack()
infinitely.
Signed-off-by: NGraf Yang <graf.yang@analog.com>
Signed-off-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NBryan Wu <cooloney@kernel.org>

arch/blackfin/mm/isram-driver.c

@@ -125,7 +125,7 @@ static bool isram_check_addr(const void *addr, size_t n)
 {
 	if ((addr >= (void *)L1_CODE_START) &&
 	    (addr < (void *)(L1_CODE_START + L1_CODE_LENGTH))) {
-		if ((addr + n) >= (void *)(L1_CODE_START + L1_CODE_LENGTH)) {
+		if ((addr + n) > (void *)(L1_CODE_START + L1_CODE_LENGTH)) {
 			show_stack(NULL, NULL);
 			printk(KERN_ERR "isram_memcpy: copy involving %p length "
 					"(%zu) too long\n", addr, n);