LU-11014 mdc: remove obsolete intent opcodes

LU-11014 mdc: remove obsolete intent opcodes

In enum ldlm_intent_flags, remove the obsolete constants IT_UNLINK,
IT_TRUNC, IT_EXEC, IT_PIN, IT_SETXATTR. Remove any handling code for
these opcodes.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I66f20e4c881cb77a481805a148a33f1c2daa5f0c
Reviewed-on: https://review.whamcloud.com/32361
Reviewed-by: Fan Yong <fan.yong@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>