stand: tftp.c doesn't need bootinfo.h

tftp.c includes bootinfo.h, but doesn't need it. Remove it, and remove
the -Istand/common from CFALGS since that's the only reason we had it.

Sponsored by:		Netflix
Reviewed by:		tsoome
Differential Revision:	https://reviews.freebsd.org/D35928

stand/libsa/Makefile

@@ -171,7 +171,6 @@ SRCS+=	time.c
 SRCS+=ffs_subr.c ffs_tables.c
 
 CFLAGS.dosfs.c+= -I${LDRSRC}
-CFLAGS.tftp.c+= -I${LDRSRC}
 CFLAGS.ufs.c+= -I${LDRSRC}
 CFLAGS.gzipfs.c+= ${ZLIB_CFLAGS}
 CFLAGS.pkgfs.c+= ${ZLIB_CFLAGS}

stand/libsa/tftp.c

@@ -55,7 +55,6 @@ __FBSDID("$FreeBSD$");
 
 #include <string.h>
 
-#include <bootstrap.h>
 #include "stand.h"
 #include "net.h"
 #include "netif.h"