V4L/DVB (7032): tda18271: tda18271_cal_on_startup should be declared static

This module option variable is only handled within the file tda18271-fe.c -

Declare this variable as static.

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