Add DSCR SPR to sysfs

[Paul Mackerras]

Anton Blanchard writes:

> POWER6 adds a new SPR, the data stream control register (DSCR). It can
> be used to adjust how agressive the prefetch mechanisms are.
> 
> Its possible we may want to context switch this, but for now just export
> it to userspace via sysfs so we can adjust it.

I think you need to adjust both CPU_FTRS_POWER6 and CPU_FTRS_POWER6X
in include/asm-powerpc/cputable.h, don't you?  Your patch doesn't
apply cleanly on Linus' current tree.  Please send a rebased patch.

Thanks,
Paul.