dmaengine: ste_dma40: Don't configure runtime configurable setup during allocate

Using the dmaengine API for slave transfers, allocating and configuring
a channel are two separate actions. Here we're removing logical channel
configuration from the channel allocation routine for slave transfers,
as the same config is already done in the runtime config function, and
put the corresponding call into d40_config_memcpy() for the memcpy
code path.

Cc: Dan Williams <djbw@fb.com>
Cc: Per Forlin <per.forlin@stericsson.com>
Cc: Rabin Vincent <rabin@rab.in>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
[Edited the commit message]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>