KVM: SVM: Separate recalc_intercepts() into nested vs. non-nested parts

KVM: SVM: Separate recalc_intercepts() into nested vs. non-nested parts

Extract the non-nested aspects of recalc_intercepts() into a separate
helper, svm_mark_intercepts_dirty(), to make it clear that the call isn't
*just* recalculating (vmcb02's) intercepts, and to not bury non-nested
code in nested.c.

As suggested by Yosry, opportunistically prepend "nested_vmbc02_" to
recalc_intercepts() so that it's obvious the function specifically deals
with recomputing intercepts for L2.

No functional change intended.

Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Link: https://patch.msgid.link/20260218230958.2877682-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>