x86: Fix tst-cpu-features-cpuinfo on Ryzen 9 (BZ #27873)

AMD define different flags for IRPB, IBRS, and STIPBP [1], so new
x86_64_cpu are added and IBRS_IBPB is only tested for Intel.

The SSDB is also defined and implemented different on AMD [2],
and also a new AMD_SSDB flag is added.  It should map to the
cpuinfo 'ssdb' on recent AMD cpus.

It fixes tst-cpu-features-cpuinfo and tst-cpu-features-cpuinfo-static
on recent AMD cpus.

Checked on x86_64-linux-gnu on AMD Ryzen 9 5900X.

[1] https://developer.amd.com/wp-content/resources/Architecture_Guidelines_Update_Indirect_Branch_Control.pdf
[2] https://bugzilla.kernel.org/show_bug.cgi?id=199889



Reviewed-by: H.J. Lu <hjl.tools@gmail.com>