Revert "libxtables: Promote xtopt_esize_by_type() as xtopt_psize getter"

Revert "libxtables: Promote xtopt_esize_by_type() as xtopt_psize getter"

This reverts commit 786b75f7c9b9feaa294da097c2e9727747162c79.

The internal routine xtopt_esize_by_type() is *not* just a fancy wrapper
around direct xtop_psize array access, as clearly indicated by the
comment right above it: It will return the single field size for
range-value types (XTTYPE_UINT*RC).

Using it in xtables_option_metavalidate() leads to spurious "memory
block of wrong size" complaints.

Fixes: 786b75f7c9b9f ("libxtables: Promote xtopt_esize_by_type() as xtopt_psize getter")
Signed-off-by: Phil Sutter <phil@nwl.cc>