s390/perf: Return error when debug_register fails

[ Upstream commit ec0c0bb489727de0d4dca6a00be6970ab8a3b30a ]

Return an error when the function debug_register() fails allocating
the debug handle.
Also remove the registered debug handle when the initialization fails
later on.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>