[ar71xx] dir-825-b1: Fix wholeflash images: Attempting to flash a wholeflash (-openwr...

[ar71xx] dir-825-b1: Fix wholeflash images: Attempting to flash a wholeflash (-openwrt) image from the normal image would brick (but recoverable via emergency flash) the router if the wholeflash image was larger than the maximum size for a normal image.  First we rename the -openwrt images to -wholeflash since -openwrt is really too generic.  We also revert the changes to the regular dir-825-b1 image, which now is the same as before, but add a -towholeflash image which is almost the same as the regular dir-825-b1 image, but copies caldata to new location and allows flashing of images that use the full flash (except u-boot, u-boot-env, and caldata paritition space) (these are the -wholeflash images).

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@33447 3c298f89-4303-0410-b956-a3cf2f4a3e73