Deefine symbolic names for some register bits, and use some that
have already been defined.
Also convert some register values from hex to decimal when it improves
readability.
IPVP_PRIORITY_MASK is corrected from (0x1F << 16) to (0xF << 16), in
conjunction with making wider use of the symbolic name. I looked at
Freescale and IBM MPIC docs and at the base OpenPIC spec, and all three
had priority as 4 bits rather than 5. Plus, the magic nubmer that is
being replaced with symbolic values treated the field as 4 bits wide.
Signed-off-by: Scott Wood <scottwood@freescale.com> Signed-off-by: Alexander Graf <agraf@suse.de>