exfat: fix wrong size update of stream entry by typo

exfat: fix wrong size update of stream entry by typo

commit 41e3928f8c58184fcf0bb22e822af39a436370c7 upstream.

The stream.size field is updated to the value of create timestamp
of the file entry. Fix this to use correct stream entry pointer.

Fixes: 29bbb14bfc80 ("exfat: fix incorrect update of stream entry in __exfat_truncate()")
Signed-off-by: Hyeongseok Kim <hyeongseok@gmail.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>