The display requires some milliseconds between GPIO_TFT_VA_EN
and GPIO_DISPLAY_ENABLE. Reorder initialisation to comply with
the display spec.

Also tune timings for better compliance with the spec.
Signed-off-by: Sven Neumann <s.neumann@raumfeld.com>
Acked-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>