KVM: SVM: Simplify MSR interception logic for IA32_XSS MSR

KVM: SVM: Simplify MSR interception logic for IA32_XSS MSR

Use svm_set_intercept_for_msr() directly to configure IA32_XSS MSR
interception, ensuring consistency with other cases where MSRs are
intercepted depending on guest caps and CPUIDs.

No functional change intended.

Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://lore.kernel.org/r/20250612081947.94081-3-chao.gao@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>