gpu: pvr: pdump: reduce error propagation from pdump to userspace

gpu: pvr: pdump: reduce error propagation from pdump to userspace

When pdump logging fails, the driver should, as much as possible,
continue working. Bad arguments should however be flagged.

This allows for a rewrite of DbgWrite()/PdumpWriteILock() to pdump_write().

Also remove the parameter write in PDumpPDDevPAddrKM, this parameter data
is simply not referenced and the data sent to the script anyway.

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