LU-12856 target: check FLFLAGS are valid while accessing them

LU-12856 target: check FLFLAGS are valid while accessing them

While checking OBD_FL_SHORT_IO flag check first that OBD_MD_FLFLAGS
are valid.

Lustre-change: https://review.whamcloud.com/36632
Lustre-commit: 707f5a982e895c9a484dcdb8d1644e3f63c7c5cc

Signed-off-by: Mikhail Pershin <mpershin@whamcloud.com>
Change-Id: I04ac61141d70883c29a113fac3985ac81cc878af
Reviewed-by: Patrick Farrell <farr0186@gmail.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/37000
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>