The number of serial interfaces for the chip 8250 can be configured at build time. This is currently not configurable and is always set to 16 interfaces. This is too little for some small embedded devices and too much for others (x86_64). Therefore, this commit creates the possibility to set this at compile time. Signed-off-by: Florian Eckert <fe@dev.tdt.de> Link: https://github.com/openwrt/openwrt/pull/19217 Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>