media: atmel-isi: drop unnecessary while loop

As there is no way this can loop it actually makes no sense to have
a while(1){} around the body - all three possible paths end in a return
statement.

Fixes: commit c1d82b89

 "[media] atmel-isi: move out of soc_camera to atmel"

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>