powerpc/pseries: Export hardware trace macro dump via debugfs

This patch adds debugfs interface to export Hardware Trace Macro (HTM)
function data in a LPAR. New hypervisor call "H_HTM" has been
defined to setup, configure, control and dump the HTM data.
This patch supports only dumping of HTM data in a LPAR.
New debugfs folder called "htmdump" has been added under
/sys/kernel/debug/arch path which contains files need to
pass required parameters for the H_HTM dump function. New Kconfig
option called "CONFIG_HTMDUMP" is added in platform/pseries
for the same.

With this module loaded, list of files in debugfs path

/sys/kernel/debug/powerpc/htmdump
coreindexonchip  htmtype  nodalchipindex  nodeindex  trace

Signed-off-by: Abhishek Dubey <adubey@linux.ibm.com>
Co-developed-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Reviewed-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250113164039.302017-2-adubey@linux.ibm.com