V4L/DVB (10123): em28xx: fix reversed definitions of I2S audio modes

Noticed when doing the audio support for the Pinnacle PCTV HD Ultimate 808e
that the modes were incorrect (the 808e uses I2S in 5 sample mode)

Thanks for Ray Lu from Empia for providing the em2860/em2880 datasheet.

Signed-off-by: Devin Heitmueller <dheitmueller@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>