commit 8f7b8db6 upstream.

The channel switch command for 6000 series devices
is larger than the maximum inline command size of
320 bytes. The command is therefore refused with a
warning. Fix this by allocating the command and
using the NOCOPY mechanism.
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>