net: myri10ge: Change variable type to bool

There is the rc variable on both myri10ge_ss_lock_napi and
myri10ge_ss_lock_poll functions. In both cases rc is only assigned the
values true and false. Both functions already return bool. Change rc
type to bool.

The simplified semantic patch that find this problem is as
follows (http://coccinelle.lip6.fr/

):

@exists@
type T;
identifier b;
@@
- T
+ bool
  b = ...;
  ... when any
  b = \(true\|false\)

Signed-off-by: Peter Senna Tschudin <peter.senna@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>