tools/rtla: Enhance argument parsing in timerlat_load.py

The enhancements made to timerlat_load.py are aimed at improving the clarity of argument parsing.

Summary of Changes:
- The cpu argument is now specified as an integer type in the argument
  parser to enforce input validation, and the construction of affinity_mask
  has been simplified to directly use the integer value of args.cpu.
- The prio argument is similarly updated to be of integer type for
  consistency and validation, eliminating the need for the conversion of
  args.prio to an integer, as this is now handled by the argument parser.

Cc: "jkacur@redhat.com" <jkacur@redhat.com>
Cc: "lgoncalv@redhat.com" <lgoncalv@redhat.com>
Link: https://lore.kernel.org/QfgO7ayKD9dsLk8_ZDebkAV0OF7wla7UmasbP9CBmui_sChOeizy512t3RqCHTjvQoUBUDP8dwEOVCdHQ5KvVNEiP69CynMY94SFDERWl94=@protonmail.com


Signed-off-by: Furkan Onder <furkanonder@protonmail.com>
Reviewed-by: Tomas Glozar <tglozar@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>