staging: ks7010: use CIRC_CNT_TO_END macro in cnt_smeqbody

This commit changes custom implementation of CIRC_CNT_TO_END.
Just use the linux kernel header one to simplify code.

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