hugetlbfs: correct obsolete function name in hugetlbfs_read_iter()

Since commit 36e7891 ("kill do_generic_mapping_read"), the function
do_generic_mapping_read() is renamed to do_generic_file_read(). And then
commit 47c27bc ("fs: pass iocb to do_generic_file_read") renamed it
to generic_file_buffered_read(). So replace do_generic_mapping_read() with
generic_file_buffered_read() to keep comment uptodate.

Link: https://lkml.kernel.org/r/20210118063210.47118-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/hugetlbfs/inode.c

@@ -310,7 +310,7 @@ hugetlbfs_read_actor(struct page *page, unsigned long offset,
 
 /*
  * Support for read() - Find the page attached to f_mapping and copy out the
- * data. Its *very* similar to do_generic_mapping_read(), we can't use that
+ * data. Its *very* similar to generic_file_buffered_read(), we can't use that
  * since it has PAGE_SIZE assumptions.
  */
 static ssize_t hugetlbfs_read_iter(struct kiocb *iocb, struct iov_iter *to)