m68knommu: remove dead code

As CONFIG_RTC_DRV_M5441x doesn't exist because the driver never made it
upstream, there is no device to register. Remove code that is never
compiled and init_BSP() as it doesn't do anything.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>