x86/fault: Add helper for dumping RMP entries

This information will be useful for debugging things like page faults
due to RMP access violations and RMPUPDATE failures.

  [ mdr: move helper to standalone patch, rework dump logic as suggested
    by Boris. ]

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240126041126.1927228-8-michael.roth@amd.com