graphics/gdal: fix build on armv7

This port uses NEON through the sse2neon.h header. Unfortunately the
header is written such that there is no difference between m128 and
m128d, while real SSE intrinsics have such a difference. This causes
problems with some template functions down the road.

Disable NEON on armv7 to avoid this problem.

Approved by: portmgr (build fix blanket)
MFH: 2025Q3

(cherry picked from commit 487097a3d2ad2f145b5ac0b924ad734dd9dc69cc)