dmaengine: pxa: remove DBGFS_FUNC_DECL()

We already have the DEFINE_SHOW_ATTRIBUTE, There is no need to define
such a macro, so remove DBGFS_FUNC_DECL.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vkoul@kernel.org>