mips: propagate the calling convention change down into __csum_partial_copy_..._user()

and turn the exception handlers into simply returning 0, which
simplifies the hell out of things in csum_partial.S
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/mips/include/asm/checksum.h

@@ -34,25 +34,17 @@
  */
 __wsum csum_partial(const void *buff, int len, __wsum sum);
 
-__wsum __csum_partial_copy_from_user(const void *src, void *dst,
-				     int len, __wsum sum, int *err_ptr);
-__wsum __csum_partial_copy_to_user(const void *src, void *dst,
-				   int len, __wsum sum, int *err_ptr);
+__wsum __csum_partial_copy_from_user(const void __user *src, void *dst, int len);
+__wsum __csum_partial_copy_to_user(const void *src, void __user *dst, int len);
 
 #define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
 static inline
 __wsum csum_and_copy_from_user(const void __user *src, void *dst, int len)
 {
-	__wsum sum = ~0U;
-	int err = 0;
-
 	might_fault();
-
 	if (!access_ok(src, len))
 		return 0;
-	sum = __csum_partial_copy_from_user((__force void *)src, dst,
-						     len, sum, &err);
-	return err ? 0 : sum;
+	return __csum_partial_copy_from_user(src, dst, len);
 }
 
 /*
@@ -62,16 +54,10 @@ __wsum csum_and_copy_from_user(const void __user *src, void *dst, int len)
 static inline
 __wsum csum_and_copy_to_user(const void *src, void __user *dst, int len)
 {
-	int err = 0;
-	__wsum sum = ~0U;
-
 	might_fault();
 	if (!access_ok(dst, len))
 		return 0;
-	sum = __csum_partial_copy_to_user(src,
-					   (__force void *)dst,
-					   len, sum, &err);
-	return err ? 0 : sum;
+	return __csum_partial_copy_to_user(src, dst, len);
 }
 
 /*
@@ -79,10 +65,10 @@ __wsum csum_and_copy_to_user(const void *src, void __user *dst, int len)
  * we have just one address space, so this is identical to the above)
  */
 #define _HAVE_ARCH_CSUM_AND_COPY
-__wsum __csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum);
+__wsum __csum_partial_copy_nocheck(const void *src, void *dst, int len);
 static inline __wsum csum_partial_copy_nocheck(const void *src, void *dst, int len)
 {
-	return __csum_partial_copy_nocheck(src, dst, len, 0);
+	return __csum_partial_copy_nocheck(src, dst, len);
 }
 
 /*