Update Mobile_Detect.php

Made detection about twice faster, by:
- Removing redundant regex that would have been matched before (e.g. iPad, Sony Tablet, Novo7),
- Merging the long lists of Samsung devices (and some others) so that the regex engine can easily skip to the next section if it doesn't start with a recognizable pattern such as GT- or SGH-,
- Shorter code (about 3KB saved) is always a bit faster to parse and thus execute...