LU-9859 mdd: unwind md_capable()

LU-9859 mdd: unwind md_capable()

The inline function md_capable() is just a wrapper
around cap_raised() which adds little benefit. Lets
just remove the use of this wrapper.

Change-Id: I1a5f4b2e34b4cf358b52b3fc4bdeff17fdab50c9
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/44580
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Aurelien Degremont <degremoa@amazon.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>