virtio-net: remove redundant truesize check with PAGE_SIZE

The truesize is guaranteed not to exceed PAGE_SIZE in
get_mergeable_buf_len(). It is saved in mergeable context, which is not
changeable by the host side, so the check in receive path is quite
redundant.

Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
Link: https://patch.msgid.link/20250630144212.48471-3-minhquangbui99@gmail.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>