staging/comedi: Use && instead of & for logical comparision

sparse complains that:
drivers/staging/comedi/drivers/adl_pci9118.c:813 pci9118_calc_divisors()
warn: maybe use && instead of &

usessh is used as a boolean flag (0 and 1) and is compared to a boolean
value so we should use && here.

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>