gpu: pvr: pdump: clean up logic across pdump.c

gpu: pvr: pdump: clean up logic across pdump.c

This patch is the least obvious of the set. It removes useless
variables, superfluous calculations, cleans up loops, and makes a few
functions wrap others instead of copying them.

Should be no functional change, but as said, very non-obvious.

Signed-off-by: Luc Verhaegen <libv@codethink.co.uk>
Signed-off-by: Imre Deak <imre.deak@nokia.com>