IB/core: Fix typo in the name of the tag-matching cap struct

The tag matching functionality is implemented by mlx5 driver
by extending XRQ, however this internal kernel information was
exposed to user space applications with *xrq* name instead of *tm*.

This patch renames *xrq* to *tm* to handle that.

Fixes: 8d50505a

 ("IB/uverbs: Expose XRQ capabilities")
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>