dmaengine: shdma: Remove sh_dmae_slave_chan_id enum

This patch replaces the sh_dmae_slave_chan_id enum
with an unsigned int. The purpose of this chainge is
to make it possible to separate the slave id enums
from the dmaengine header.

The slave id enums varies with processor model, so in
the future it makes sense to put these in the processor
specific headers together with the pinmux enums.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>