Add radio support for the Thomson DTT7612 tuner.

This tuner uses a different 1st intermediate frequency than the other radio
tuners supported (a lot of NTSC radio tuners probably need this change too).

Add a new tuner-simple parameter, radio_if.  It selects the 1st IF used for
radio reception.  The radio frequency setting code in tuner-simple now uses
this field, instead of a special case select() block for each tuner with radio
support.

The tuner parameters for tuners that used a 33.3 MHz RIF now set radio_if to 1
in tuner-types.c.

The Thomson DTT7612 gets radio_if = 2, also add has_tda9887 = 1 and
fm_gain_normal = 1.

Add some defines for tda9887 bits that control IF setting in radio mode.

Add a new tda9887 config option, TDA9887_RIF_41_3, that selects a 41.3 MHz
radio IF.

Fix the way tda9887 radio options work.  The driver was modifying the default
radio mode config templates based on the TDA9887_XXXX flags.  This means that
_all_ tuners would get the same settings.  If you had a one tuner than used
TDA9887_GAIN_NORMAL and one that didn't, both would get the setting.  Now the
tda9987 driver just checks if tuner mode is radio and then applies the config
settings directly to the data being sent, just like how all the TV mode
settings already work.

The PLL setting math is made a little more accurate.

And a grammar error in a printk is fixed.
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>