Revert "alpha: fix broken network checksum"

This reverts commit b93b90ff, which
was commit 0ef38d70 upstream.
It was intended to fix a regression which never occurred in 3.2.

arch/alpha/lib/csum_partial_copy.c

@@ -373,11 +373,6 @@ csum_partial_copy_from_user(const void __user *src, void *dst, int len,
 __wsum
 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
 {
-	__wsum checksum;
-	mm_segment_t oldfs = get_fs();
-	set_fs(KERNEL_DS);
-	checksum = csum_partial_copy_from_user((__force const void __user *)src,
+	return csum_partial_copy_from_user((__force const void __user *)src,
 			dst, len, sum, NULL);
-	set_fs(oldfs);
-	return checksum;
 }