ARM: dts; gta04: SPI panel chip select is active low

With the arrival of

commit 2fee9583 ("spi: dt-bindings: clarify CS behavior for spi-cs-high and gpio descriptors")

it was clarified what the proper state for cs-gpios should be, even if the
flag is ignored. The driver code is doing the right thing since

766c6b63 ("spi: fix client driver breakages when using GPIO descriptors")

The chip-select of the td028ttec1 panel is active-low, so we must omit spi-cs-high;
attribute (already removed by separate patch) and should now use GPIO_ACTIVE_LOW for
the client device description to be fully consistent.

Fixes: 766c6b63

 ("spi: fix client driver breakages when using GPIO descriptors")
CC: stable@vger.kernel.org
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>