I have got the kernell build whit no error's.
This i think the solution is:
When i add the component to the system in SOPC builder the name is "opencores_i2c_0"
i rename it to "i2c_0" in the SOPC builder, the name in the nios2_system.h changes also. You must rerun SOPC an Quartus.
Then i build the kernell en there where only error's on "i2c_1" and not on "i2c_0".
I add a second i2c master to SOPC and also rename it to "i2c_1" then the kernell build;s wihout error's
I don't have my kit with me so i will upload the kernell tomorrow and see if it is working.
I it 22:00 hour at The Netherland now
So it is just a name problem !!! I let you know if it is working tommorow