The generic name is too generic and when it appears on its
own, for example nano_generic_defconfig, it is not
visible what the file is about, so call it generic_arc the same
way the Kconfig platform is called.
Change-Id: Icf737f305d84142dad4f52fd26a5c7481f9fc5be
Signed-off-by: Anas Nashif <anas.nashif@intel.com>