target/i386: Enable support for XSAVES based features

target/i386: Enable support for XSAVES based features

There're some new features, including Arch LBR, depending
on XSAVES/XRSTORS support, the new instructions will
save/restore data based on feature bits enabled in XCR0 | XSS.
This patch adds the basic support for related CPUID enumeration
and meanwhile changes the name from FEAT_XSAVE_COMP_{LO|HI} to
FEAT_XSAVE_XCR0_{LO|HI} to differentiate clearly the feature
bits in XCR0 and those in XSS.

Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
Message-Id: <20220215195258.29149-5-weijiang.yang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>