media: dvb-frontends/stv6111: cleanup and fix licensing boilerplates

media: dvb-frontends/stv6111: cleanup and fix licensing boilerplates

The stv6111.h doesn't carry any header nor any licensing boilerplate at
all, so copy this from the main driver file stv6111.c.

[mchehab@kernel.org: kept only the part of this patch that copied
 the license from stv6111.c into stv6111.h]

Cc: Ralph Metzler <rjkm@metzlerbros.de>
Cc: Manfred Voelkel <mvoelkel@DigitalDevices.de>
Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>