x86-64: Small improvements to dl-trampoline.S

1.  Remove sse2 instructions when using the avx512 or avx version.

2.  Fixup some format nits in how the address offsets where aligned.

3.  Use more space efficient instructions in the conditional AVX
    restoral.
        - vpcmpeqq          -> vpcmpeqb
        - cmp imm32, r; jz  -> inc r; jz

4.  Use `rep movsb` instead of `rep movsq`. The former is guranteed to
    be fast with the ERMS flags, the latter is not. The latter also
    wastes an instruction in size setup.