staging: atomisp: silence an array overflow warning

Static checkers complain that we should check if "i" is in bounds
before we check if "var8[i]" is a NUL char.  This bug is harmless but
also easy to fix.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>