V4L/DVB (6074): tuner: fix ifdef tags to match actual file name

The file, tuner-driver.h was originally named tuner-hw.h, but we decided to
rename it.  At the time, I had forgotten to change the #ifdef __TUNER_HW_H__
to #ifdef __TUNER_DRIVER_H__ .  This patch corrects that.

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>