x86: drop EVEX table entries that can be served by VEX ones

x86: drop EVEX table entries that can be served by VEX ones

The duplication is not only space inefficient, but also risks entries
going out of sync (some of which that I became aware of while doing this
work will get addressed subsequently). Right here note that for
VGF2P8MULB this also addresses the prior lack of EVEX.W decoding (i.e. a
first example of out of sync entries).

This introduces EXxEVexR to some VEX templates, on the basis that this
operand is benign there and only relevant when EVEX encoding ends up
reaching these entries.