plain_store: use lower log priority when sha1 not cached

This is actually not an error.  sd_debug() is more appropriate.

Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Signed-off-by: Liu Yuan <namei.unix@gmail.com>
recovery: fix log priority and output

This is not an error.  sd_info() is better.

Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Signed-off-by: Liu Yuan <namei.unix@gmail.com>