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/stfs.c

@@ -0,0 +1,41 @@
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <asm/uaccess.h>
+
+#include "soft-fp.h"
+#include "double.h"
+#include "single.h"
+
+int
+stfs(void *frS, void *ea)
+{
+	FP_DECL_D(A);
+	FP_DECL_S(R);
+	float f;
+	int err;
+
+#ifdef DEBUG
+	printk("%s: S %p, ea %p\n", __FUNCTION__, frS, ea);
+#endif
+
+	__FP_UNPACK_D(A, frS);
+
+#ifdef DEBUG
+	printk("A: %ld %lu %lu %ld (%ld)\n", A_s, A_f1, A_f0, A_e, A_c);
+#endif
+
+	FP_CONV(S, D, 1, 2, R, A);
+
+#ifdef DEBUG
+	printk("R: %ld %lu %ld (%ld)\n", R_s, R_f, R_e, R_c);
+#endif
+
+	err = _FP_PACK_CANONICAL(S, 1, R);
+	if (!err || !__FPU_TRAP_P(err)) {
+		__FP_PACK_RAW_1(S, &f, R);
+		if (copy_to_user(ea, &f, sizeof(float)))
+			return -EFAULT;
+	}
+
+	return err;
+}