x86/HVM: reduce scope of pfec in hvm_emulate_init_per_insn()

x86/HVM: reduce scope of pfec in hvm_emulate_init_per_insn()

It needs calculating only in one out of three cases. Re-structure the
code a little such that the variable truly gets calculated only when we
don't get any insn bytes from elsewhere, and hence need to (try to)
fetch them. Also OR in PFEC_insn_fetch right in the initializer.

While in this mood, restrict addr's scope as well.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Paul Durrant <pdurrant@amazon.com>