V4L/DVB (3318): Fixes warning: variable "ret" is used before its value is set

- Fixes compiling warning on kernel 2.6.15 with the Intel C compiler. 
- It said drivers/media/dvb/frontends/bcm3510.c(258): 
  warning #592: variable "ret" is used before its value is set

Signed-off-by: Patrick Boettcher <pb@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@brturbo.com.br>