utils/genrandconfig: disallow configs with BR2_XTENSA_CUSTOM=y
When BR2_XTENSA_CUSTOM=y is used with the internal toolchain, an
overlay file is mandatory, which genrandconfig can't provide. So we
simply disallow such configurations.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit c81da5e41c8b8863920a1f0416e4f7f4d22788bf)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>