dm persistent data: remove CONFIG_EXPERIMENTAL

The CONFIG_EXPERIMENTAL config item has not carried much meaning for a
while now and is almost always enabled by default. As agreed during the
Linux kernel summit, remove it from any "depends on" lines in Kconfigs.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

drivers/md/persistent-data/Kconfig

 config DM_PERSISTENT_DATA
        tristate
-       depends on BLK_DEV_DM && EXPERIMENTAL
+       depends on BLK_DEV_DM
        select LIBCRC32C
        select DM_BUFIO
        ---help---