powerpc: move math-emu over to arch/powerpc

Towards the goal of having arch/powerpc not build anything over in arch/ppc
move math-emu over.  Also, killed some references to arch/ppc/ in the
arch/powerpc Makefile which should belong in drivers/ when the particular
sub-arch's move over to arch/powerpc.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/math-emu/fres.c

@@ -0,0 +1,12 @@
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <asm/uaccess.h>
+
+int
+fres(void *frD, void *frB)
+{
+#ifdef DEBUG
+	printk("%s: %p %p\n", __FUNCTION__, frD, frB);
+#endif
+	return -ENOSYS;
+}