[media] smiapp: Remove unused function

smiapp_replace_limit_at() function is not called by the driver.
This was detected by sparse as:
drivers/media/i2c/smiapp/smiapp-quirk.c:64:5: warning:
symbol 'smiapp_replace_limit_at' was not declared. Should it be static?

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>