This commit adds a new template, Vector1Vs1VdMaskDeclare, to replace
the use of Vector1Vs1RdMaskDeclare in Vector1Vs1VdMaskFormat.
The change addresses the issue with the number of indices in srcRegIdxArr.
Only two indices are available in Vector1Vs1RdMaskDeclare, but instructions
that use Vector1Vs1VdMaskFormat, like 'vmsbf', require three indices
(for vs1, vs2(old_vd), and vm) to function correctly.
Change-Id: I0c966e11289ce07efcc3b0cc56948311289530ad