usr.sbin/pkg: Don't re-define roundup2

The file already includes sys/param.h and should use that definition.
I found this while testing D28332.

Reviewed By:	bapt
Differential Revision: https://reviews.freebsd.org/D28331

usr.sbin/pkg/config.c

@@ -47,8 +47,6 @@ __FBSDID("$FreeBSD$");
 
 #include "config.h"
 
-#define roundup2(x, y)	(((x)+((y)-1))&(~((y)-1))) /* if y is powers of two */
-
 struct config_value {
        char *value;
        STAILQ_ENTRY(config_value) next;