Fix the memory layout for the VT4.x.
Fix the memory layout for the VT4.x.

The VT4.x memory layout appears to be slightly different from the Atom
3.x memory layout. The logbook ringbuffer does start at offset 0x420
instead of 0x400.

Poltsi/libdivecomputer-vms,josh-wambua/libdivecomputer,henrik242/libdivecomputer,venkateshshukla/libdivecomputer,henrik242/libdivecomputer,josh-wambua/libdivecomputer,glance-/libdivecomputer,venkateshshukla/libdivecomputer,glance-/libdivecomputer