net: ep93xx_eth: drop GFP_DMA from call to dma_alloc_coherent()

Commit a197b59a (mm: fail GFP_DMA allocations when ZONE_DMA is not
configured) made page allocator to return NULL if GFP_DMA is set but
CONFIG_ZONE_DMA is disabled.

This causes ep93xx_eth to fail:

 WARNING: at mm/page_alloc.c:2251 __alloc_pages_nodemask+0x11c/0x638()
 Modules linked in:
 [<c0035498>] (unwind_backtrace+0x0/0xf4) from [<c0043da4>] (warn_slowpath_common+0x48/0x60)
 [<c0043da4>] (warn_slowpath_common+0x48/0x60) from [<c0043dd8>] (warn_slowpath_null+0x1c/0x24)
 [<c0043dd8>] (warn_slowpath_null+0x1c/0x24) from [<c0083b6c>] (__alloc_pages_nodemask+0x11c/0x638)
 [<c0083b6c>] (__alloc_pages_nodemask+0x11c/0x638) from [<c00366fc>] (__dma_alloc+0x8c/0x3ec)
 [<c00366fc>] (__dma_alloc+0x8c/0x3ec) from [<c0036adc>] (dma_alloc_coherent+0x54/0x60)
 [<c0036adc>] (dma_alloc_coherent+0x54/0x60) from [<c0227808>] (ep93xx_open+0x20/0x864)
 [<c0227808>] (ep93xx_open+0x20/0x864) from [<c0283144>] (__dev_open+0xb8/0x108)
 [<c0283144>] (__dev_open+0xb8/0x108) from [<c0280528>] (__dev_change_flags+0x70/0x128)
 [<c0280528>] (__dev_change_flags+0x70/0x128) from [<c0283054>] (dev_change_flags+0x10/0x48)
 [<c0283054>] (dev_change_flags+0x10/0x48) from [<c001a720>] (ip_auto_config+0x190/0xf68)
 [<c001a720>] (ip_auto_config+0x190/0xf68) from [<c00233b0>] (do_one_initcall+0x34/0x18c)
 [<c00233b0>] (do_one_initcall+0x34/0x18c) from [<c0008400>] (kernel_init+0x94/0x134)
 [<c0008400>] (kernel_init+0x94/0x134) from [<c0030858>] (kernel_thread_exit+0x0/0x8)

Since there is no restrictions for DMA on ep93xx, we can fix this by just
removing the GFP_DMA flag from the call.

Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Tested-by: Petr Stetiar <ynezz@true.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>