[media] R820T tuner needs CONFIG_BITREVERSE

In a rarely hit randconfig case, the r820t tuner driver can
get built when CONFIG_BITREVERSE is not selected by any
other driver, resulting in this error:

drivers/built-in.o: In function `r820t_read.constprop.3':
:(.text+0xa0594): undefined reference to `byte_rev_table'

For consistency, this adds the 'select BITREVERSE' that
all other similar drivers have.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>