Is there a superfine option for older camera models in chdk ?
No.
CHDK's "SuperFine" option just activates the Canon SF mode on cameras where Canon disabled this mode in the menu.
And my camera itself has superfine(jpeg) quality option in its normal setting menus, is it same thing?
Yes.
But im using crw(in dng format) for maximum quality.
So the JPEG setting doesn't matter at all...
RAW files are always unmodified sensor data, no setting (neither in CHDK nor in the Canon menu) does influence the quality of the raw image.
Only the badpixel mapping may change some pixels (in RAW and in JPEG images) to eliminate defective pixels.