sparc: remove unused "config BITS"

sparc's asm/module.h got removed in commit
786d35d4 ("Make most arch asm/module.h
files use asm-generic/module.h"). That removed the only two uses of this
Kconfig symbol. So we can remove its entry too.

> >From arch/sparc/Makefile:
>     ifeq ($(CONFIG_SPARC32),y)
>     [...]
>
>     [...]
>     export BITS    := 32
>     [...]
>
>     else
>     [...]
>
>     [...]
>     export BITS   := 64
>     [...]
>
> So $(BITS) is set depending on whether CONFIG_SPARC32 is set or not.
> Using $(BITS) in sparc's Makefiles is not using CONFIG_BITS. That
> doesn't count as usage of "config BITS".

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>