[media] dib8000: report Interleaving 4 correctly

On ISDB-T, the valid values for interleaving are 0, 1, 2 and 4.
While the first 3 are properly reported, the last one is reported
as 3 instead. Fix it.

Tested with a Dektec DTA-2111 RF generator.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Acked-by: Patrick Boettcher <pboettcher@kernellabs.com>