mn10300: fix build error of missing fpu_save()

mn10300: fix build error of missing fpu_save()

[ Upstream commit 3705ccfdd1e8b539225ce20e3925a945cc788d67 ]

When CONFIG_FPU is not enabled on arch/mn10300, <asm/switch_to.h> causes
a build error with a call to fpu_save():

  kernel/built-in.o: In function `.L410':
  core.c:(.sched.text+0x28a): undefined reference to `fpu_save'

Fix this by including <asm/fpu.h> in <asm/switch_to.h> so that an empty
static inline fpu_save() is defined.

Link: http://lkml.kernel.org/r/dc421c4f-4842-4429-1b99-92865c2f24b6@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>