[POWERPC] Remove unused header file: arch/ppc/syslib/cpc710.h.

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>