Initializes seqDumpPos on qiodevice.cpp

Initializes seqDumpPos on qiodevice.cpp

This was spotted by RIM static code checking team. seqDumpPos is a dummy
variable which is only used on sequential mode. It is used as a
simultaneous storage area of both pPos and pDevicePos when in sequential mode,
to keep both in sync. They just suggested that it would be a good practice to
initialize the variable, since it does not have any side effect, and there's
not much value on not doing it.

Change-Id: I8138729eb31df5779c91b368c2cfaecd39788f29
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>
Reviewed-by: Jonas Gastal <jgastal@profusion.mobi>