Move tuners to common/tuners

There were several issues in the past, caused by the hybrid tuner design, since
now, the same tuner can be used by drivers/media/dvb and drivers/media/video.

This patch moves those common tuners into a common dir. It also moves saa7146
driver into drivers/media/video, where other hybrid drivers are placed.

Kconfig items were rearranged, to split V4L/DVB core from their drivers.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

From: Michael Krufky <mkrufky@linuxtv.org>

Fix the following build error:

In file included from dvb-bt8xx.c:35:
dvb-bt8xx.h:42:26: error: tuner-simple.h: No such file or directory
dvb-bt8xx.c: In function 'frontend_init':
dvb-bt8xx.c:612: error: 'simple_tuner_attach' undeclared (first use in this function)
dvb-bt8xx.c:612: error: (Each undeclared identifier is reported only once
dvb-bt8xx.c:612: error: for each function it appears in.)
dvb-bt8xx.c:612: warning: type defaults to 'int' in declaration of '__a'
dvb-bt8xx.c:612: warning: type defaults to 'int' in declaration of 'type name'
dvb-bt8xx.c:612: warning: cast from pointer to integer of different size
dvb-bt8xx.c:612: warning: type defaults to 'int' in declaration of 'type name'
dvb-bt8xx.c:612: warning: cast from pointer to integer of different size
dvb-bt8xx.c:612: error: called object '__a' is not a function
dvb-bt8xx.c:696: warning: type defaults to 'int' in declaration of '__a'
dvb-bt8xx.c:696: warning: type defaults to 'int' in declaration of 'type name'
dvb-bt8xx.c:696: warning: cast from pointer to integer of different size
dvb-bt8xx.c:696: warning: type defaults to 'int' in declaration of 'type name'
dvb-bt8xx.c:696: warning: cast from pointer to integer of different size
dvb-bt8xx.c:696: error: called object '__a' is not a function

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>

From: Trent Piepho <xyzzy@speakeasy.org>

The Makefiles in the dvb directory tree used '=' when defining EXTRA_CFLAGS
rather than '+=', which is far more common in the rest of the kernel source.

  =  14 times (9 of which this patch removes)
 :=  25 times
 += 123 times

This change also has certain advantages for the out of kernel v4l-dvb build
system.

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>

From: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Manu Abraham <manu@linuxtv.org>

- use c99 initializers
- remove blank lines
- remove bt848.h -- it's already in driver/media/video
  (this probably breaks 2.4 compilation)