target/m68k: consolidate physical translation offset into get_physical_address()

target/m68k: consolidate physical translation offset into get_physical_address()

Since all callers to get_physical_address() now apply the same page offset to
the translation result, move the logic into get_physical_address() itself to
avoid duplication.

Suggested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20200701201531.13828-3-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>