platform/x86: amd-pmc: Add support for AMD Smart Trace Buffer

platform/x86: amd-pmc: Add support for AMD Smart Trace Buffer

STB (Smart Trace Buffer), is a debug trace buffer that isolates the
failures by analyzing the last running feature of a system. This
non-intrusive way always runs in the background and stores the trace
into the SoC.

This patch enables the STB feature by passing module param
"enable_stb=1" while loading the driver and provides mechanism to
access the STB buffer using the read and write routines.

Co-developed-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Signed-off-by: Sanket Goswami <Sanket.Goswami@amd.com>
Link: https://lore.kernel.org/r/20211130112318.92850-3-Sanket.Goswami@amd.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>