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.

index 983510d282f6..db4caf2b4669 100644
@@ -258,6 +258,7 @@ config MEDIA_TUNER_R820T
 	tristate "Rafael Micro R820T silicon tuner"
 	depends on MEDIA_SUPPORT && I2C
 	default m if !MEDIA_SUBDRV_AUTOSELECT
+	select BITREVERSE
 	help
 	  Rafael Micro R820T silicon tuner driver.