configs/licheepi_zero: U-Boot needs pylibfdt
Like all Allwinner platforms, building the licheepi_zero U-Boot
configuration requires pylibfdt.
Fixes:
https://gitlab.com/buildroot.org/buildroot/-/jobs/378314331
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>