imx: ventana: enable precharge power-down fast-exit mode

Enable fast-exit precharge mode necessary for some DDR3 devices being
used on Ventana boards.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>

board/gateworks/gw_ventana/gw_ventana_spl.c

@@ -340,6 +340,7 @@ static void spl_dram_init(int width, int size_mb, int board_model)
 		.bi_on = 1,	/* Bank interleaving enabled */
 		.sde_to_rst = 0x10,	/* 14 cycles, 200us (JEDEC default) */
 		.rst_to_cke = 0x23,	/* 33 cycles, 500us (JEDEC default) */
+		.pd_fast_exit = 1, /* enable precharge power-down fast exit */
 	};
 
 	/*