stk500, _load_address(): try resetting the target in case of errors
stk500, _load_address(): try resetting the target in case of errors

Looks like the target exits programming mode after a while, and load_address
fails. Try resetting the target and reentering programming mode in case this
happens.

ciminaghi/libdfu,ciminaghi/libdfu,ciminaghi/libdfu