media: dvb-frontends/cxd2099: Kconfig additions

The cxd2099 driver makes use of the Regmap I2C kernel API, thus add
"select REGMAP_I2C" to it's Kconfig block. Also, make it default "m" if
!MEDIA_SUBDRV_AUTOSELECT, just like every other dvb-frontend driver.
And, while at it, remove the hyphens around the help tag.

Cc: Jasmin Jessich <jasmin@anw.at>
Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>