qiprog: Move device tests to a separate file

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
qiprog: Fix copy-paste error in debug message

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
qiprog: Add test to check for buffering bugs in device or driver

These tests stress set_address/readn combinations in a number of ways which
expose seemingly innocent bugs. More details in comments.

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