x86: switch 32bit csum_and_copy_to_user() to user_access_{begin,end}()

consolidate HAVE_CSUM_COPY_USER for 32bit and 64bit, while are at it
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/x86/include/asm/checksum.h

 /* SPDX-License-Identifier: GPL-2.0 */
 #define  _HAVE_ARCH_COPY_AND_CSUM_FROM_USER 1
+#define HAVE_CSUM_COPY_USER
 #ifdef CONFIG_X86_32
 # include <asm/checksum_32.h>
 #else

arch/x86/include/asm/checksum_32.h

@@ -176,7 +176,6 @@ static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 /*
  *	Copy and checksum to user
  */
-#define HAVE_CSUM_COPY_USER
 static inline __wsum csum_and_copy_to_user(const void *src,
 					   void __user *dst,
 					   int len, __wsum sum,
@@ -185,11 +184,10 @@ static inline __wsum csum_and_copy_to_user(const void *src,
 	__wsum ret;
 
 	might_sleep();
-	if (access_ok(dst, len)) {
-		stac();
+	if (user_access_begin(dst, len)) {
 		ret = csum_partial_copy_generic(src, (__force void *)dst,
 						len, sum, NULL, err_ptr);
-		clac();
+		user_access_end();
 		return ret;
 	}
 

arch/x86/include/asm/checksum_64.h

@@ -129,9 +129,6 @@ static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
  */
 extern __wsum csum_partial(const void *buff, int len, __wsum sum);
 
-#define HAVE_CSUM_COPY_USER 1
-
-
 /* Do not call this directly. Use the wrappers below */
 extern __visible __wsum csum_partial_copy_generic(const void *src, const void *dst,
 					int len, __wsum sum,