PolicyAttrs::IsUnspecified is modified in
RVV::Intrinsic::computeBuiltInTypes and used under
RVVIntrinsic::updateNamesAndPolicy. Suprisingly the modification
in RVV::Intrinsic::computeBuiltInTypes is completely unnecessary.
This commit removes the redundant logic.
This is the 4th commit of a patch-set that aims to change the default policy
for RVV intrinsics from TAMU to TAMA.
Please refer to the cover letter in the 1st commit (D141573) for an