MLK-15110-17 gpu: imx: dpu: fetchdecode: Add helper fetchdecode_set_burstlength()
This patch adds helper fetchdecode_set_burstlength() so that
the burst length of fetchdecode can be set to appropriate value.
When we don't use prefetch engine, the burst length is set to
the maximal value - 16. When we use prefetch engine, the burst
length should make the buffer base address align to burst size
but not greater than 16. This alignment operation can address
the issue recorded by TKT343664.
Signed-off-by: Liu Ying <victor.liu@nxp.com>