Set LCDC_PALETTE_LOAD_MODE bit-field with new tilcdc_write_mask()
instead of tilcdc_set(). Setting a bit-fields with tilcdc_set() is
fundamentally broken.
Signed-off-by: Jyri Sarha <jsarha@ti.com>
Tested-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>