graphics/lux: unbreak on armv7

An upcoming patch will fix the misconfiguration that restricts the
address space for armv7 processes on arm64 to ~2GB instead of the ~3.5GB
it should have been. With that patch applied, the port builds fine.
As a temporary workaround, the following sysctls can be set to effect
the same change (though affecting arm64 processes too):

kern.maxssiz=67108864
kern.maxdsiz=536870912

armv6 stays broken as we cannot run armv6 processes on arm64 (see
PR #256132).

PR: 274705
MFH: 2023Q4
See also: https://reviews.freebsd.org/D42451