libceph: fix log output race condition in OSD client

libceph: fix log output race condition in OSD client

OSD client logging has a problem in get_osd() and put_osd().
For one logging output refcount_read() is called twice. If recount
value changes between both calls logging output is not consistent.

This patch prints out only the resulting value.

[ idryomov: don't make the log messages more verbose ]

Signed-off-by: Simon Buttgereit <simon.buttgereit@tu-ilmenau.de>
Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>