[sfputil] fix firmware download progress not show 100%

[rqx110]

What I did

resolve #3266

correct the progress value disaplay when file is download complete

How I did it

How to verify it

run the command, and veriry the output

Previous command output (if the output of a command-line utility has changed)

root@sonic:/tmp# sfputil firmware download Ethernet0 /var/tmp/xxxx.bin
CDB: Starting firmware download
Platform doesn't implement optoe write max change. Skipping value increase.
Downloading ...  [###################################-]   99%  00:00:00
Platform doesn't implement optoe write max change. Skipping value restore!
CDB: firmware download complete

New command output (if the output of a command-line utility has changed)

root@sonic:/tmp# sfputil firmware download Ethernet0 /var/tmp/xxxx.bin
CDB: Starting firmware download
Platform doesn't implement optoe write max change. Skipping value increase.
Downloading ...  [####################################]  100%
Platform doesn't implement optoe write max change. Skipping value restore!
CDB: firmware download complete

[rqx110]

Can some one review this? @prgeor