[POWERPC] ppc32: fix CPCI405 board support

Hi,

this patch brings the CPCI405 board support up to date and fixes several
outstanding issues:

       -add bios_fixup()
       -enable RTC only when CONFIG_GEN_RTC defined
       -corrected CompactPCI interrupt map
       -added cpci405_early_serial_map for correct UART clocking
       -removed unused code

Matthias

Signed-off-by: Matthias Fuchs <matthias.fuchs@esd-electronics.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>