Change WARNING: Image is flipped. Regenerate it using PVRTexTool

[lrrrs]

Since 3.1 you have to use flipped PVR textures (Took me quite a while to figure out...),
but when you use them you get a warning that's confusing:

CCTexturePVR.m:

if( flipped )
CCLOGWARN(@"cocos2d: WARNING: Image is flipped. Regenerate it using PVRTexTool");

This needs to be changed into the opposite:

if( !flipped )
CCLOGWARN(@"cocos2d: WARNING: Image is NOT flipped. Regenerate it using PVRTexTool");

This way I would have found the issue way earlier. So please think of other developers which will run into the same "strange" issues ;)

[s1ddok]

Edited warning in 3.5