staging: ks7010: factor out send_request_to_device function

In all functions related with requests to the device the same
patter in used and is also adding a comment to make clear the
intention of the code. Just factor out the pattern into a new
send_request_to_device function to improve readability and make
clear code intention.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>