[compiler-rt][AArch64] NFCI: Remove sme-abi-vg.c (#119193)

Given that FMV support is required for the SME builtins to be built, the
FMV constructor as defined in:

  compiler-rt/lib/builtins/cpu_model/aarch64.c

already initialises the feature bits, so there's no need to create
another one.

GitOrigin-RevId: bbd99d903ec956b5cc87c544854337da8db2d2bf
2 files changed