dt/documentation: add specification of dma bus information
dt/documentation: add specification of dma bus information

Recently we introduced the generic device tree infrastructure for couple of DMA
bus parameter, dma-ranges and dma-coherent. Update the documentation so that
its useful for future users.

The "dma-ranges" property is intended to be used for describing the
configuration of DMA bus RAM addresses and its offset w.r.t CPU addresses.

The "dma-coherent" property is intended to be used for identifying devices
supported coherent DMA operations.

Cc: Arnd Bergmann <f2c659f01951776204a6c5b902787d9019fbeebd@arndb.de>
Cc: Grant Likely <9069e6f5a2b566e2674a0ba1e2bf39c12c195fad@linaro.org>
Cc: Rob Herring <988782c95b9025801edfc9a5b1fd5a8e93699e07@kernel.org>
Cc: Pawel Moll <9508d67e84a03f69673bee3bb7ec593a47efeb0d@arm.com>
Cc: Mark Rutland <1db9dd262beaa64f35756dd39531d9747b7778bb@arm.com>
Cc: Ian Campbell <ea71a0dcef14058f83aacb9a32bd3c02e11f589b@hellion.org.uk>
Cc: Kumar Gala <383ef5577c6e1178b93f59ec8d0936f76d2a98c4@codeaurora.org>
Acked-by: Shawn Guo <912cf7eb7d8018e2943586ae6657d21fd4e38239@freescale.com>
Signed-off-by: Grygorii Strashko <bfa0a1520768723a1c60e18250fb841c342eb8d8@ti.com>
Signed-off-by: Santosh Shilimkar <5b4d8dc9ea337fff5fd1729321eda9873ade0b09@ti.com>
Signed-off-by: Rob Herring <fbb37eacae100e13076d5c4b46f06cfa4d6fa9f8@kernel.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs