Set the malloc alignment to 64 bytes on platforms that use the U-Boot API
device drivers.  Recent versions of u-boot run with the MMU enabled, and
require DMA-based I/O to be aligned to cache line boundaries.

These changes are based on a patch originally submitted by Juergen Weiss,
but I reworked them and thus any problems are purely my fault.

Submitted by:	"Juergen Weiss" <weiss@uni-mainz.de>
Reviewed by:	imp, nwhitehorn, jhb
- Implement the RX EARLYOFF and RXDV GATED bits as done by RealTek's Linux
  driver as version 8.037.00 for RTL8168{E-VL,EP,F,G,GU} and RTL8111B. This
  makes reception of packets work with the RTL8168G (HW rev. 0x4c000000) in
  my Shuttle DS47.
- Consistently use RL_MSI_MESSAGES.
In joint forces with:	yongari

MFC after:	5 days