dmaengine: st_fdma: Update st_fdma to 'depends on REMOTEPROC'.

During randconfig builds you can get the following warning
"warning: (ST_FDMA) selects ST_SLIM_REMOTEPROC which has unmet direct
 dependencies (REMOTEPROC)"

randconfig builds should always build without any warnings so
update fdma to depend on REMOTEPROC so this can not happen.

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>