Documentation/bindings: crypto: remove the dma-mask property

The dma-mask property is broken and was removed in the device trees
having a safexcel-eip197 node and in the safexcel cryptographic
driver. This patch removes the dma-mask property from the documentation
as well.

Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>