mips: sanitize __access_ok()

for one thing, the last argument is always __access_mask and had been such
since 2.4.0-test3pre8; for another, it can bloody well be a static inline -
-O2 or -Os, __builtin_constant_p() propagates through static inline calls.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/mips/oprofile/backtrace.c

@@ -18,7 +18,7 @@ struct stackframe {
 static inline int get_mem(unsigned long addr, unsigned long *result)
 {
 	unsigned long *address = (unsigned long *) addr;
-	if (!access_ok(VERIFY_READ, addr, sizeof(unsigned long)))
+	if (!access_ok(VERIFY_READ, address, sizeof(unsigned long)))
 		return -1;
 	if (__copy_from_user_inatomic(result, address, sizeof(unsigned long)))
 		return -3;