rds: don't operate for rds_tcp

The current code implicitly assumes that the system is using rds_rdma.
If the module runs on a system with rds_tcp loaded, we get a traceback
ending in the following error:

  KeyError: 'rds_ib_devices'

I don't know whether rds_tcp support is desired at this time, but at a
minimum, corelens should not throw a traceback. So, explicitly require
rds_rdma for this module. Now, for rds_tcp, we get the following
standard corelens warning that explains the situation.

  warning: rds skipped because 'rds, rds_rdma' was (were) not (all) loaded in the kernel

Orabug: 37502613

Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>

Author: brenns10

drgn_tools/rds.py

@@ -1540,7 +1540,7 @@ class Rds(CorelensModule):
     """Print info about RDS devices, sockets, connections, and stats"""
 
     name = "rds"
-    skip_unless_have_kmods = ["rds"]
+    skip_unless_have_kmods = ["rds_rdma", "rds"]
 
     # We access information from the following modules #
     debuginfo_kmods = ["mlx5_core", "mlx4_core", "mlx5_ib", "mlx4_ib"]