board/raspberrypi: fix rpi4/rpi4-64 genimage config files
Since commit 'package/rpi-firmware: fix startup file names' ([1]) the
start and fixup file names are normalized to start.elf/fixup.dat,
adjust the rpi4 genimage config files accordingly.
Fixes:
ERROR: file(rpi-firmware/fixup4.dat): stat(.../images/rpi-firmware/fixup4.dat) failed: No such file or directory
ERROR: vfat(boot.vfat): could not setup rpi-firmware/fixup4.dat
[1] https://git.buildroot.net/buildroot/commit/?id=
1bdc0334ff6273761b2e7fda730cdcc7e1f46862
Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>