media: pci/ivtv: Replace GPLv2 boilerplate text with SPDX

The FSF does not reside in 59 Temple Place anymore, so we should
not ask the people to write to that address in case they need a
copy of the GPL.

Anyway, all other files in this directory already had their boilerplate
text replaced by a proper SPDX tag in the earlier commit 1a59d1b8
("treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156"),
so let's do the same in the remaining files now, too.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>