ARM: PL08x: move AHB master port selection into prep_* functions

As we initialize the default cctl value in the prep_* functions along
with the increment settings, we don't need to repeat the selection of
the AHB ports each time we create a LLI entry.  Do this in the prep_*
functions once per transfer.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>