exfat: move setting VOL_DIRTY over exfat_remove_entries()

Move setting VOL_DIRTY over exfat_remove_entries() to avoid unneeded
leaving VOL_DIRTY on -ENOTEMPTY.

Fixes: 5f2aa075 ("exfat: add inode operations")
Cc: stable@vger.kernel.org # v5.7
Reported-by: Tetsuhiro Kohada <kohada.t2@gmail.com>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>