ventana: add memory configuration for IMX6DL/1GB

The GW5300 standard board has an IMX6DL with a 800MHz DDR3 memory interface
and 1GB of memory.  This adds a propper config file for that combination.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
ventana: remove obsolete cfg file

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
ventana: set DRAM_RESET DDR_SEL properly

DDR_SEL should be set to 00b per the discussion at:
https://community.freescale.com/thread/315242

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
ventana: adjust default DIO padconf

Configure default DIO padconf as:
 - 100k pull-up
 - 34ohm drive strength (9.7mA drive)
 - fast slew rate
 - medium (200MHz) switching speed
 - hysteresis enabled

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