MLK-15110-19 gpu: imx: dpu: fetchdecode: Fixup stride when we use prefetch

MLK-15110-19 gpu: imx: dpu: fetchdecode: Fixup stride when we use prefetch

When we use prefetch, we use DPR and PRG to do frame input cropping.  Thus,
the stride of fetchdecode is the stride of cropped frame, which means the
value of the stride is cropped_width * bytes_per_pixel.  Also, to address
TKT339017, when we use prefetch engine for fetchdecode, we need to round
the frame stride up to the fetchdecode burst size, i.e., burst length
multiplies 8 bytes.  According to TKT343664, the buffer base address has
to align to burst size, so we'll pick an appropriate burst size value in
fetchdecode_source_stride().

Signed-off-by: Liu Ying <victor.liu@nxp.com>