anv: Accurately advertise dynamic descriptor limits

The number of dynamic descriptors is limited by both the number of
descriptors and the total number of dynamic things.  Because there isn't
a single "maximum dynamic things" limit, we need to divide by two so
that they can create the maximum of both UBOs and SSBOs.

Reviewed-by: Eduardo Lima Mitev <elima@igalia.com>
Cc: "17.0 13.0" <mesa-stable@lists.freedesktop.org>
(cherry picked from commit 5e44ef4a76d9a3681fb6be605319250d4ab800ee)
diff --git a/src/intel/vulkan/anv_device.c b/src/intel/vulkan/anv_device.c
index 9d21290..67323e0 100644
--- a/src/intel/vulkan/anv_device.c
+++ b/src/intel/vulkan/anv_device.c
@@ -533,9 +533,9 @@
       .maxPerStageResources                     = 128,
       .maxDescriptorSetSamplers                 = 256,
       .maxDescriptorSetUniformBuffers           = 256,
-      .maxDescriptorSetUniformBuffersDynamic    = 256,
+      .maxDescriptorSetUniformBuffersDynamic    = MAX_DYNAMIC_BUFFERS / 2,
       .maxDescriptorSetStorageBuffers           = 256,
-      .maxDescriptorSetStorageBuffersDynamic    = 256,
+      .maxDescriptorSetStorageBuffersDynamic    = MAX_DYNAMIC_BUFFERS / 2,
       .maxDescriptorSetSampledImages            = 256,
       .maxDescriptorSetStorageImages            = 256,
       .maxDescriptorSetInputAttachments         = 256,