dmaengine: coh901318: fix function return types build warnings

A recent patch that removed coh901318_control() replaced it
with a number of pointers to existing functions, but those
unfortunately have the wrong return  type and need to be
changed to return an 'int' with an error value rather than
a 'void' to avoid these build warnings:

drivers/dma/coh901318.c:2697:32: warning: assignment from incompatible pointer type
  base->dma_slave.device_config = coh901318_dma_set_runtimeconfig;
                                ^
drivers/dma/coh901318.c:2698:31: warning: assignment from incompatible pointer type
  base->dma_slave.device_pause = coh901318_pause;
                               ^
drivers/dma/coh901318.c:2699:32: warning: assignment from incompatible pointer type
  base->dma_slave.device_resume = coh901318_resume

The coh901318_base_init function has the correct return type
already, but needs to be marked 'static' to avoid a sparse
warning about a missing declaration.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 6782af11 ("dmaengine: coh901318: Split device_control")
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>