qed: add missing header dependencies

We get 4 warnings when building kernel with W=1:
drivers/net/ethernet/qlogic/qed/qed_selftest.c:6:5: warning: no previous prototype for 'qed_selftest_memory' [-Wmissing-prototypes]
drivers/net/ethernet/qlogic/qed/qed_selftest.c:19:5: warning: no previous prototype for 'qed_selftest_interrupt' [-Wmissing-prototypes]
drivers/net/ethernet/qlogic/qed/qed_selftest.c:32:5: warning: no previous prototype for 'qed_selftest_register' [-Wmissing-prototypes]
drivers/net/ethernet/qlogic/qed/qed_selftest.c:55:5: warning: no previous prototype for 'qed_selftest_clock' [-Wmissing-prototypes]

In fact, these functions are declared in qed_selftest.h, so this patch
add missing header dependencies.

Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Acked-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>