RDS: Move rds_rtd definitions from rds_rt_debug files to common files

RDS: Move rds_rtd definitions from rds_rt_debug files to common files

This patch moves rds_rtd definitions from rds_rtd_debug.h to rds.h and
rds_rt_debug_bitmap modparam definition from rds_rt_debug.c to af_rds.c.
The patch removes rds_rt_debug files since there isn't much content
in these files to be held separately.

Commit 'ib/rds: runtime debuggability enhancement' originally defined
rds_rtd definitions.

Orabug: 23294707

Signed-off-by: Avinash Repaka <avinash.repaka@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>