staging/slicoss: Check pointer before dereferencing

Smatch complains that the variable adapter is dereferenced before it is
checked:
slicoss.c:906 slic_timer_load_check() warn: variable dereferenced before
check 'adapter' (see line 904)

-> move the assignment after the check.

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