Pull up following revision(s) (requested by rin in ticket #730):

sys/arch/powerpc/conf/files.powerpc: revision 1.93
sys/arch/powerpc/include/pio.h: revision 1.8
sys/arch/powerpc/pic/intr.c: revision 1.27
sys/arch/powerpc/powerpc/bus_dma.c: revision 1.50
sys/arch/powerpc/powerpc/pio_subr.S: revision 1.17

Add PPC_IBM440 flag as 440 is significantly different from 40x processors.
(It may be more easily supported by booke than by ibm4xx.)

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eieio is implemented as sync on 40x. Therefore, "sync; eieio" and
"eieio; sync" can be replaced by a single sync.

(martin)