modules: lvgl: Add support for NXP PXP engine

Adds support for the NXP PXP engine. LVGL changed
the Kconfig symbol from LV_USE_GPU_NXP_PXP to
LV_USE_PXP, but hal_nxp still relies on
LV_USE_GPU_NXP_PXP, so add a temporary symbol for it.
Additionally the drawing engines need to invalidate
ranges in the dcache, the method needs to be provided
via a lvgl_support.h file.

Signed-off-by: Fabian Blatz <fabianblatz@gmail.com>