LU-11014 mdt: remove enum mdt_it_code

LU-11014 mdt: remove enum mdt_it_code

Remove enum mdt_it_code, struct mdt_it_flavor and the mdt_it_flavor
array. In mdt_intent_opc, collapse the switch statement followed by
array lookup into a single switch statement that assigns the intent
format, handler, and handler flags. Simplify the subsequent logic in
mdt_intent_opc() accordingly.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: Id56fe5fa1bd4d4c03a8de2db9d39f571bed06b2f
Reviewed-on: https://review.whamcloud.com/32358
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>