fix assignment in if-clause in smsc(4)

[Ricardo Mestre]

Hi,

smsc(4) needs a fix to an assignment which I found with cppcheck. FreeBSD also
made this change 2 years ago on rev 295608.

OK?

Index: if_smsc.c
===================================================================
RCS file: /cvs/src/sys/dev/usb/if_smsc.c,v
retrieving revision 1.31
diff -u -p -u -r1.31 if_smsc.c
--- if_smsc.c   29 Jul 2017 17:24:04 -0000      1.31
+++ if_smsc.c   24 Aug 2018 10:31:21 -0000
@@ -774,7 +774,7 @@ smsc_chip_init(struct smsc_softc *sc)
        smsc_write_reg(sc, SMSC_PM_CTRL, SMSC_PM_CTRL_PHY_RST);
 
        if ((err = smsc_wait_for_bits(sc, SMSC_PM_CTRL,
-           SMSC_PM_CTRL_PHY_RST) != 0)) {
+           SMSC_PM_CTRL_PHY_RST)) != 0) {
                smsc_warn_printf(sc, "timed-out waiting for phy reset to "
                    "complete\n");
                goto init_failed;