dmaengine: qcom: bam_dma: rename BAM_MAX_DATA_SIZE define

It seems that the define has not been with acurate name and
makes confusion while reading the code. The more acurate
name should be BAM_FIFO_SIZE.

Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Reviewed-by: Andy Gross <andy.gross@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>