pan/bi: bump iter_count to 2000

Without this, we fail to register-allocate the shader used in the
dEQP-VK.ssbo.phys.layout.random.8bit.scalar.78 VK-CTS test case.

Yeah, this sucks, but failing to compile sucks even more. We need a new
register allocator plan here.

Acked-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33124>

src/panfrost/compiler/bi_ra.c

@@ -1083,7 +1083,7 @@ bi_register_allocate(bi_context *ctx)
    struct lcra_state *l = NULL;
    bool success = false;
 
-   unsigned iter_count = 1000; /* max iterations */
+   unsigned iter_count = 2000; /* max iterations */
 
    /* Number of bytes of memory we've spilled into */
    unsigned spill_count = ctx->info.tls_size;