bnx2x: Move statistics implementation into semaphores

bnx2x: Move statistics implementation into semaphores

Commit dff173de84958 ("bnx2x: Fix statistics locking scheme") changed the
bnx2x locking around statistics state into using a mutex - but the lock
is being accessed via a timer which is forbidden.

[If compiled with CONFIG_DEBUG_MUTEXES, logs show a warning about
accessing the mutex in interrupt context]

This moves the implementation into using a semaphore [with size '1']
instead.

Signed-off-by: Yuval Mintz <[email protected]>
Signed-off-by: Ariel Elior <[email protected]>
Signed-off-by: David S. Miller <[email protected]>