Add allowed notations section for genimage.cfg files by specifying the
accepted suffix or prefix. Note that "K" has been decided to specify
KiloBytes as 1024 bytes. This has been done because in Buildroot the 90%
of the cases were using "K" and not "k".
Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>