The Nomadik PL080 variant has some extra protection bits that
may be set, so we need to check these bits to see if the
channels are actually available for the DMAengine to use.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: Alim Akhtar <alim.akhtar@gmail.com>
Cc: Alessandro Rubini <rubini@gnudd.com>
Reviewed-by: NViresh Kumar <viresh.kumar@st.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NVinod Koul <vinod.koul@linux.intel.com>