powerpc/44x: Fix PCI node in Yosemite DTS

The stanza for PCI was copied from Bamboo which has four PCI slots.  Yosemite
only has one PCI slot which is mapped to IDSEL 12, ADDR 22, IRQ2 Vector 25,
INTA.

Signed-off-by: Curtis Wald <cwald@watchguardvideo.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>