net: libwx: handle page_pool_dev_alloc_pages error

net: libwx: handle page_pool_dev_alloc_pages error

page_pool_dev_alloc_pages could return NULL. There was a WARN_ON(!page)
but it would still proceed to use the NULL pointer and then crash.

This is similar to commit 001ba0902046
("net: fec: handle page_pool_dev_alloc_pages error").

This is found by our static analysis tool KNighter.

Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
Fixes: 3c47e8ae113a ("net: libwx: Support to receive packets in NAPI")
Reviewed-by: Joe Damato <jdamato@fastly.com>
Link: https://patch.msgid.link/20250407184952.2111299-1-chenyuan0y@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>