LU-9855 obdclass: cleanup obd_class.h defines

LU-9855 obdclass: cleanup obd_class.h defines

Get rid of OBT and CTXTP defines.
Remove OBD_CHECK_DT_OP
Convert EXP_CHECK_MD_OP into a function.
Remove CTXT_CHECK_OP.

Signed-off-by: Ben Evans <bevans@cray.com>
Change-Id: Ia2adc579602818ebdba0a40c99da9e3af1575d24
Reviewed-on: https://review.whamcloud.com/29286
Tested-by: Jenkins
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Steve Guminski <stephenx.guminski@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>