V4L/DVB (7440): dvb-bt8xx: fix build error

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