e1000: remove workaround for Errata 23 from jumbo alloc

According to the comment, errata 23 says that the memory we allocate
can't cross a 64KiB boundary. In case of jumbo frames we allocate
complete pages which can never cross the 64KiB boundary because
PAGE_SIZE should be a multiple of 64KiB so we stop either before the
boundary or start after it but never cross it. Furthermore the check
seems bogus because it looks at skb->data which is not seen by the HW
at all because we only pass the DMA address of the page we allocated. So
I *think* the workaround is not required here.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>