Remove obsolete asf(8)

kgdb now handles kernel module state internally, so the asf tool serves
no purpose.

PR:		229046
Reviewed by:	brooks
Relnotes:	yes
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D15827

targets/pseudo/userland/Makefile.depend

@@ -810,7 +810,6 @@ DIRDEPS.amd64= \
 	usr.sbin/acpi/acpidump \
 	usr.sbin/acpi/iasl \
 	usr.sbin/apm \
-	usr.sbin/asf \
 	usr.sbin/bhyve \
 	usr.sbin/bhyvectl \
 	usr.sbin/bhyveload \
@@ -842,7 +841,6 @@ DIRDEPS.i386= \
 	sbin/sconfig \
 	usr.sbin/apm \
 	usr.sbin/apmd \
-	usr.sbin/asf \
 	usr.sbin/btxld \
 	usr.sbin/cpucontrol \
 	usr.sbin/hyperv/tools \