arm64: PIE: Do not skip static relocation

When we build an arm64 target and enable POSITION_INDEPENDENT, we were
skipping our build-time dynamic relocation fixup routine (STATIC_RELA).

This was probably done because we didn't need it in this case, as the
PIE fixup routine in start.S would take care of that at runtime.

However when we now skip this routine (upon detecting that the fixup
offset is 0), this might lead to uninitialised pointers.

Remove the exception, so that we always do the build-time relocation.

NOTE: GNU binutils starting with v2.27.1 do this build-time relocation
automatically, to be in-line with other architecures. So on newer
toolchains our manual fixup is actually not needed. It doesn't hurt to
have it, though, so that we keep compatibility with the popular Linaro
toolchains, which lack this feature.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>