mx6sabreauto: set SYS_MALLOC_F for video
Sabre Auto boards currently hang with:
```
U-Boot
2019.07-rc3-00057-gc41940c406 (Jun 03 2019 - 14:42:41 +0200)
CPU: Freescale i.MX6QP rev1.0 996 MHz (running at 792 MHz)
CPU: Automotive temperature grade (-40C to 125C)Reset cause: WDOG
Model: Freescale i.MX6 Quad Plus SABRE Automotive Board
Board: MX6Q-Sabreauto revA
I2C: ready
DRAM: 2 GiB
Video device 'ipu@
2400000' cannot allocate frame buffer memory -ensure the device is set up before relocation
Error binding driver 'ipuv3_video': -28
Video device 'ipu@
2800000' cannot allocate frame buffer memory -ensure the device is set up before relocation
Error binding driver 'ipuv3_video': -28
Some drivers failed to bind
Error binding driver 'generic_simple_bus': -28
Some drivers failed to bind
initcall sequence
8ffe00b8 failed at call
1780e93b (err=-28)
```
Set SYS_MALLOC_F_LEN to reserve_video to work.
This is similar to the change Peng Fan did for mx6sabresd (
9002e735e717)
Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Reviewed-by: Peng Fan <peng.fan@nxp.com>