staging: ks7010: fix checkpatch memset warning

Checkpatch emits WARNING: single byte memset is suspicious. Swapped
2nd/3rd argument? Call site in question is correct but is an unusual
use of memset() to zero a single byte. The same can be achieved by
assigning 0 directly to the memory location.

Dereference pointer and assign 0 to that memory location. Use '\0' to
make explicit that it is a char pointer.

Signed-off-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>