GRU Driver: GRU instructions & macros

This patchs contains macros & inline functions used to issue instructions
to the GRU.

Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>