restapi: add replica count parameter to rsdl for remove brick

Adding replica count as an optional parameter to remove brick
action in rsdl. Bricks resource is using this  parameter but
it is missing in RSDL

Change-Id: Ice0271453cef97cef67d1ca8e767aa1558d6bb3a
Signed-off-by: Ramesh Nachimuthu <rnachimu@redhat.com>