ahci.c: remove non-existing SB600 raid id (re-send)

    SB600 RAID and SB600 SATA is the same controller and share the
same PCI ID 0x4380. There is no such PCI ID 0x4381.

    Signed-off-by: Conke Hu <conke.hu@gmail.com>
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Signed-off-by: Jeff Garzik <jeff@garzik.org>