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/lfd.c

@@ -0,0 +1,19 @@
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <asm/uaccess.h>
+
+#include "sfp-machine.h"
+#include "double.h"
+
+int
+lfd(void *frD, void *ea)
+{
+	if (copy_from_user(frD, ea, sizeof(double)))
+		return -EFAULT;
+#ifdef DEBUG
+	printk("%s: D %p, ea %p: ", __FUNCTION__, frD, ea);
+	dump_double(frD);
+	printk("\n");
+#endif
+	return 0;
+}