Commit 84ba2e8bf5f1e3a9d0d01a577f72cfd51f88a7b6 got the path to
board/friendlyarm/nanopi-neo4/ wrong in the DEVELOPERS file when
adding a new defconfig nanopi_neo4_defconfig. Let's fix the typo.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>