tools: kwbimage: Fix dumping DATA registers for v0 images

End of DATA register section is indicated by zero value in both raddr and
rdata.

So do not stop dumping registers with non-zero address and zero value.
And also print end of DATA registers section.

Fixes: 1a8e6b63 ("tools: kwbimage: Dump kwbimage config file on '-p -1' option")
Signed-off-by: Pali Rohár <pali@kernel.org>
Reported-by: Tony Dinh <mibodhi@gmail.com>
Tested-by: Tony Dinh <mibodhi@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>