pstore/platform: fix potential mem leak if pstore_init_fs failed

There is a potential mem leak when pstore_init_fs failed,
since the pstore compression maybe unlikey to initialized
successfully. We must clean up the allocation once this
unlikey issue happens.

Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
Link: https://lore.kernel.org/r/1581068800-13817-1-git-send-email-qiwuchen55@gmail.com


Signed-off-by: Kees Cook <keescook@chromium.org>