intel: Re-disable ray tracing on 32 bits

We had this disabled before moving to the common framework for BVH
building and lost it along the way.

Fixes: f0e18c475b ("intel: remove GRL/intel-clc")
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36522>

meson.build

@@ -325,8 +325,12 @@ with_any_broadcom = [
   with_broadcom_vk,
 ].contains(true)
 
+intel_vk_can_rt = host_machine.cpu_family() == 'x86_64' or \
+                  host_machine.cpu_family() == 'aarch64'
 with_intel_vk_rt = get_option('intel-rt') \
    .disable_auto_if(not with_intel_vk) \
+   .disable_if(not intel_vk_can_rt, \
+               error_message: 'Intel Ray Tracing requires 64-bit architectures') \
   .allowed()
 
 with_any_intel = [