[PATCH] ppc32: Fix building of radstone_ppc7d

Updated radstone_ppc7d_defconfig to include the ds1337 driver which is used
by the platform code.  This fixes the link error when building.
Signed-off-by: Kumar Gala <kumar.gala@freescale.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>