x86-32: Introduce CONFIG_X86_DEV_DMA_OPS

32-bit x86 systems may need their own DMA operations, so add
a new config option, which is turned on for 64-bit systems. This
patch has no functional effect but it paves the way for supporting
the STA2x11 I/O Hub and possibly other chips.

Signed-off-by: Alessandro Rubini <rubini@gnudd.com>
Link: http://lkml.kernel.org/r/f79fcc1a2e17ef942e1b798b92aac43a80202532.1333560789.git.rubini@gnudd.com


Acked-by: Giancarlo Asnaghi <giancarlo.asnaghi@st.com>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>