driver/ddr/fsl: Add workaround for A009663

driver/ddr/fsl: Add workaround for A009663

Erratum A-009663 workaround requires to set DDR_INTERVAL[BSTOPRE] to 0
before setting DDR_SDRAM_CFG[MEM_EN] and set DDR_INTERVAL[BSTOPRE]
to the desired value after DDR initialization has completed.

When DDR controller is configured to operate in auto-precharge
mode(DDR_INTERVAL[BSTOPRE]=0), this workaround is not needed.

Signed-off-by: Shengzhou Liu <Shengzhou.Liu@freescale.com>
Reviewed-by: York Sun <york.sun@nxp.com>