x86/boot: Remove cached CPUID data from the trampoline

x86/boot: Remove cached CPUID data from the trampoline

We have a cached cpuid_ext_features in the trampoline which is kept in sync by
various pieces of boot logic.  This is complicated, and all it is actually
used for is to derive whether NX is safe to use.

Replace it with a canned value to load into EFER.

trampoline_setup() and efi_arch_cpu() now tweak trampoline_efer at the point
that they are stashing the main copy of CPUID data.  Similarly,
early_init_intel() needs to tweak if it has re-enabled the use of NX.

This simplifies the AP boot and S3 resume paths by using trampoline_efer
directly, rather than locally turning FEATURE_NX into EFER_NX.

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