V4L/DVB (8549): mxl5007: Fix an error at include file

mxl5007 was forcing for its compilation:

In file included from drivers/media/common/tuners/mxl5007t.c:25:drivers/media/common/tuners/mxl5007t.h:80:1: warning: "CONFIG_MEDIA_TUNER_MXL5007T" redefined
In file included from <command-line>:0:
./include/linux/autoconf.h:2782:1: warning: this is the location of the previous definition

Probably, some temporary hack for testing.

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