media: dvb_dummy_fe: place EXPORT_SYMBOL below corresponding function

dvb_dummy_fe.c had all its EXPORT_SYMBOL macros located at the end of the
file. Now these are located directly below the symbol they are exporting
for increased readability.

Suggested-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>