i386: apm(4): apm_thread(): sleep without lbolt

[Scott Cheloha]

Here's another sleep that doesn't need lbolt.

The idea here is to call apm_periodic_check() once a second.
We can do that without lbolt.

Is there some other address that would be more appropriate for this
thread to sleep on?  It doesn't look like any apm(4) code calls
wakeup(9) on lbolt so I've just replaced with with a local channel.

ok?

Index: apm.c
===================================================================
RCS file: /cvs/src/sys/arch/i386/i386/apm.c,v
retrieving revision 1.125
diff -u -p -r1.125 apm.c
--- apm.c       24 Jun 2020 22:03:40 -0000      1.125
+++ apm.c       12 Dec 2020 01:17:38 -0000
@@ -50,6 +50,7 @@
 #include <sys/buf.h>
 #include <sys/reboot.h>
 #include <sys/event.h>
+#include <sys/time.h>
 
 #include <machine/conf.h>
 #include <machine/cpu.h>
@@ -904,12 +905,13 @@ void
 apm_thread(void *v)
 {
        struct apm_softc *sc = v;
+       int chan;
 
        for (;;) {
                rw_enter_write(&sc->sc_lock);
                (void) apm_periodic_check(sc);
                rw_exit_write(&sc->sc_lock);
-               tsleep_nsec(&lbolt, PWAIT, "apmev", INFSLP);
+               tsleep_nsec(&chan, PWAIT, "apmev", SEC_TO_NSEC(1));
        }
 }