gpu: pvr: pdump: remove page offset juggling

gpu: pvr: pdump: remove page offset juggling

The offset from the start of the page never changes when changing
address spaces, just the page address changes.

If an out of place assert is removed, (as all it could change is
the address printed in an error message), then BM_GetPhysPageAddr()
takes any address, and returns the physical address of the page.
It can deal with an offset, and will return the page address
without offset.

These two facts were used to reduce the address wrangling logic even
further.

An obviously wrong masking was fixed in PDumpMem2KM.

Signed-off-by: Luc Verhaegen <Luc.Verhaegen@basyskom.de>
Signed-off-by: Imre Deak <imre.deak@nokia.com>