ofwdump: install dependent on MK_FDT

The utility depends on the presence of the openfirm(4) pseudo-device,
which is gated by the FDT kernel option. The MK_FDT knob is correctly
set to "yes" for FDT/OFW-enabled platforms (powerpc* included); use it
to install the utility and eliminate the arch-specific Makefile logic.

No functional change intended.

Reviewed by:	emaste, pkubaj
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D41977

tools/build/mk/OptionalObsoleteFiles.inc

@@ -2016,6 +2016,7 @@ OLD_DIRS+=usr/share/examples/ypldap
 .endif
 
 .if ${MK_FDT} == no
+OLD_FILES+=usr/sbin/ofwdump
 OLD_FILES+=usr/share/man/man8/ofwdump.8.gz
 .endif
 

usr.sbin/Makefile

@@ -133,6 +133,7 @@ SUBDIR.${MK_EFI}+=	efivar efidp efibootmgr efitable efiwake
 .if ${MK_OPENSSL} != "no"
 SUBDIR.${MK_EFI}+=	uefisign
 .endif
+SUBDIR.${MK_FDT}+=	ofwdump
 SUBDIR.${MK_FLOPPY}+=	fdcontrol
 SUBDIR.${MK_FLOPPY}+=	fdformat
 SUBDIR.${MK_FLOPPY}+=	fdread

usr.sbin/Makefile.aarch64

@@ -2,4 +2,3 @@
 .if ${MK_ACPI} != "no"
 SUBDIR+=	acpi
 .endif
-SUBDIR+=	ofwdump

usr.sbin/Makefile.arm

@@ -1,2 +0,0 @@
-
-SUBDIR+=	ofwdump

usr.sbin/Makefile.powerpc

@@ -2,4 +2,3 @@
 .if ${MACHINE_ARCH} != "powerpcspe"
 SUBDIR+=	nvram
 .endif
-SUBDIR+=	ofwdump

usr.sbin/Makefile.riscv

@@ -1,2 +0,0 @@
-
-SUBDIR+=	ofwdump