Blackfin Ethernet MAC driver: fix bug Report returned -ENOMEM upwards (in case L1/uncached memory alloc fails)

Bug tracker: https://blackfin.uclinux.org/gf/project/uclinux-dist/tracker/?action=TrackerItemEdit&tracker_item_id=3399Signed-off-by: NMichael Hennerich <michael.hennerich@analog.com>
Signed-off-by: NBryan Wu <bryan.wu@analog.com>

This patch implements the driver necessary use the Analog Devices
Blackfin processor's on-chip ethernet MAC controller.

[try#2]
 - add timeout control
 - kill dma_config_reg bitfields
 - some trivial cleanup

[try#3]
 - add endianess check
 - add DRV_NAME, DRV_VERSION... driver information string
 - add some comments for silicon anomaly and dma API confusion
 - some code trivial cleanup

[try#4]
 - add Blackfin latest GPIO pin mux opertion with Michael Hennerich's
  help and Dan's review
 - rewrite the DMA descriptor list operation in a more readable way
  by Joe's review

[try#5]
 - cleanup some coding style by Joe's review.

[try#6]
 - 1.1 version fix a bug when set up multicast list pointed by Mr. yoshfuji
 - rearrange the desc_list_free function.
Signed-off-by: NMichael Hennerich <michael.hennerich@analog.com>
Signed-off-by: NBryan Wu <bryan.wu@analog.com>
Cc: Michael Buesch <mb@bu3sch.de>
Cc: Mike Frysinger <vapier.adi@gmail.com>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Williams <dcbw@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NJeff Garzik <jeff@garzik.org>