media: vidtv: psi: fix missing assignments in while loops

Some variables were only assigned once but were used in while
loops as if they had been updated at every iteration. Fix this.

Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>