I managed to work it out; by running

make kernel_menuconfig ; make

I was able to select the staging drivers option, and build the FBTFT driver into the kernel image. Now my only problem is that the MT7628 SPI driver won't accept transfers larger than 16 bytes at a time, but that's an issue for another day

I've made use of notro's FBTFT driver in the past for running an ILI9341-based LCD on embedded linux devices, but I can't seem to work out how to get the driver to build with the LEDE build system. Google searches aren't currently turning up anything useful either

The most frustrating thing is that the code is there in the staging sub-tree of the kernel drivers, but I can't enable the options to select staging drivers in the menuconfig, as well as turning on the framebuffer support needed to take advantage of the display.

Any help would be appreciated!