Both allnodes and devtree_lock are defined in common code.  The
extern declaration should be in the common header too so that the
compiler can type check.  allnodes is already in of.h, but
devtree_lock should be declared there too.

This patch removes the SPARC declarations and uses decls in of.h instead.
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: NMichal Simek <monstr@monstr.eu>
Acked-by: NDavid S. Miller <davem@davemloft.net>