IB/hfi1: Set in_use_ctxts bits for user ctxts only

The in_use_ctxts bitmask is for user receive contexts only.  Setting it for
any other type of receive context is incorrect.

Move initial set of in_use_ctxts bits from the general context init to the
user context specific init. Having this bit set can allow contexts to be
incorrectly identified by some IRQ handlers. This will allow
handle_user_interrupt() will now filter user contexts correctly.

Clean up redundant is_rcv_urgent_int() user context check.

A follow on patch will clean up an incorrect code path in the
is_rcv_avail_int().

Fixes: 8737ce95 ("IB/hfi1: Fix an assign/ordering issue with shared context IDs")
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-by: Kamenee Arumugam <kamenee.arumugam@intel.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>