[PATCH] i2c: allow building emev2 without slave mode again

[Arnd Bergmann]

On Sunday 13 December 2015 10:09:59 Wolfram Sang wrote:
> 
> What about not ifdeffing the inline function and keep the build error
> whenever someone uses it without I2C_SLAVE being selected?

The inline function is only added there for the case that I2C_SLAVE is
disabled, so that would be pointless.

However, what we could do is move the extern declaration outside of
the #ifdef to make it always visible. The if(IS_ENABLED(CONFIG_I2C_SLAVE))
check should then ensure that it never actually gets called, and we
get a link error if some driver gets it wrong.

	Arnd