x86/cpuid: Drop get_cpu_vendor() completely

x86/cpuid: Drop get_cpu_vendor() completely

get_cpu_vendor() tries to do a number of things, and ends up doing none of
them well.

For calculating the vendor itself, use x86_cpuid_lookup_vendor() which is
implemented in a far more efficient manner than looping over cpu_devs[].

For setting up this_cpu, set it up once on the BSP only, rather than
latest-takes-precident across the APs.  Such a system is probably not going to
boot, but this feels like a less dangerous course of action.  Adjust the
printed errors to be more clear in the mismatch case.

This removes the only user of cpu_dev->c_ident[], so drop that field as well.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>