The device sig it's reporting is for the ATMEGA328P and not the ATMEGA8A.
Looks like it's trying to flash your Arduino and not the USBASP.
You should select 'Arduino as ISP' for the programmer in the IDE and not AVRISP MkII.
IIRC, in Linux, the USB port is like /dev/ttyUSB0 or something like that.
These are just comments, they may not be pertinent.
Concerning the signature issue: I'm not sure that you should set the self programming jumper (I don't have an USBASP), since you are using an external programmer to upload.