gpu: imx: Drop parts depending on IMX_DPU_CORE

Those were just removed

Signed-off-by: Guido Günther <guido.gunther@puri.sm>
2 jobs for imx8-4.18-drop-dpu in 42 minutes and 28 seconds
Status Job ID Name Coverage
  Build
passed #18980
librem5
build:aarch64:Image

00:42:28

passed #18981
librem5
build:aarch64:deb

00:26:15