vmxnet3: Suppress page allocation warning for massive Rx Data ring

The vmxnet3 driver supports an Rx Data ring (rx-mini) to optimise the
processing of small packets. The size of this ring's DMA-coherent memory
allocation is determined by the product of the primary Rx ring size and
the data ring descriptor size:

sz = rq->rx_ring[0].size * rq->data_ring.desc_size;

When a user configures the maximum supported parameters via ethtool
(rx_ring[0].size = 4096, data_ring.desc_size = 2048), the required
contiguous memory allocation reaches 8 MB (8,388,608 bytes).

In environments lacking Contiguous Memory Allocator (CMA),
dma_alloc_coherent() falls back to the standard zone buddy allocator. An
8 MB allocation translates to a page order of 11, which strictly exceeds
the default MAX_PAGE_ORDER (10) on most architectures.

Consequently, __alloc_pages_noprof() catches the oversize request and
triggers a loud kernel warning stack trace:

WARN_ON_ONCE_GFP(order > MAX_PAGE_ORDER, gfp)

This warning is unnecessary and alarming to system administrators because
the vmxnet3 driver already handles this allocation failure gracefully.
If dma_alloc_coherent() returns NULL, the driver safely disables the
Rx Data ring (adapter->rxdataring_enabled = false) and falls back to
standard, streaming DMA packet processing.

To resolve this, append the __GFP_NOWARN flag to the dma_alloc_coherent()
gfp_mask. This instructs the page allocator to silently fail the
allocation if it exceeds order limits or memory is too fragmented,
preventing the spurious warning stack trace.

Furthermore, enhance the subsequent netdev_err() fallback message to
include the requested allocation size. This provides critical debugging
context to the administrator (e.g., revealing that an 8 MB allocation
was attempted and failed) without making hardcoded assumptions about
the state of the system's configurations.

Reviewed-by: Jijie Shao <shaojijie@huawei.com>
Signed-off-by: Aaron Tomlin <atomlin@atomlin.com>
Link: https://patch.msgid.link/20260226163121.4045808-1-atomlin@atomlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>