Not necessarily, no. There is a long history of people releasing closed source drivers, particularly on embedded platforms.
So far as I can tell the kernel devs think it's harmful and A Bad Thing (TM), but not a violation.
Also as has been pointed out below, it wouldn't automatically make it GPL. It would make it in violation of GPL and releasing under GPL would fix the violation, but it wouldn't make it GPL.
There's a 10-year-old post to LKML from Linus saying the GPL nature of kernel modules is a huge grey area. I don't think it's been resolved since then.
Licenses aren't applied automatically. What can happen is for Samsung to get sued for a violation of GPL and either be forced to license the code under GPL or pay damages.
As the others have said, no it would not make it GPL.
However, the customers who bought such devices could try sue for feeling mislead as a customer. If Samsung ever used the word free, open, or even linux, they might be liable under false advertising consumer protection laws. Keyword here is might, and is likely to vary based on where you live.
If enough people did this, samsung would likely feeling pressured to relicense the necessary (sold) kernel modules as GPL.
