nir/lower_memcpy: Don't mask the store

For constant-size memcpys, we can do as much as a vec4 at a time.  We
were accidentally masking the store to only the .x component.

Fixes: a3177cca996145 "nir: Add a lowering pass to lower memcpy"
Reviewed-by: Jesse Natalie <jenatali@microsoft.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7305>
diff --git a/src/compiler/nir/nir_lower_memcpy.c b/src/compiler/nir/nir_lower_memcpy.c
index ab29144..9ffb3bf 100644
--- a/src/compiler/nir/nir_lower_memcpy.c
+++ b/src/compiler/nir/nir_lower_memcpy.c
@@ -74,7 +74,7 @@
    index = nir_i2i(b, index, nir_dest_bit_size(parent->dest));
    assert(parent->deref_type == nir_deref_type_cast);
    deref = nir_build_deref_ptr_as_array(b, parent, index);
-   nir_store_deref(b, deref, value, 1);
+   nir_store_deref(b, deref, value, ~0);
 }
 
 static void