radv: Fix architecture in radeon_icd.{arch}.json

radv: Fix architecture in radeon_icd.{arch}.json

Use the host arch, not the target arch. In Meson and in recent
Autotools, the host arch is where the binary will be used. The target
arch is useful only when compiling a compiler.

See: http://mesonbuild.com/Cross-compilation.html
See: https://www.gnu.org/software/automake/manual/html_node/Cross_002dCompilation.html
Reported-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>