amd64/fpu: Track supervisor state XSAVE components

The amd64/fpu.c xsave_* routines track supported XSAVE components and
features. However, they only track supported user state components, and
there is currently no way for a consumer to check whether the CPU
supports a supervisor state component. Fix this by saving the supported
supervisor state components, enumerated by CPUID function 0DH,
sub-function 1, in a separate mask.

Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D48466