libqiprog: Shorten names of members in curr_addr_range

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
libqiprog: Rename curr_addr_range qiprog_device member to addr

The long name made this member difficult to use, as it required several
lines of code even for simple calculations. Shorten it to make it sane.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>