Avoid using 'void *' struct fields when the structs are not defined
in linux/amba/pl08x.h - instead, forward declare the struct names, and
use these instead.  This ensures we have proper typechecking.
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>