rpmball: Adjust to new rpm, do not require --force

rpmball: Adjust to new rpm, do not require --force

Also prevent warning: directory /boot: remove failed

Before:

[root@TestCloud1 xen]# rpm -hiv dist/xen*rpm
Preparing...                          ################################# [100%]
        file /boot from install of xen-4.15-unstable.x86_64 conflicts with file from package filesystem-3.2-25.el7.x86_64
        file /usr/bin from install of xen-4.15-unstable.x86_64 conflicts with file from package filesystem-3.2-25.el7.x86_64
        file /usr/lib from install of xen-4.15-unstable.x86_64 conflicts with file from package filesystem-3.2-25.el7.x86_64
        file /usr/lib64 from install of xen-4.15-unstable.x86_64 conflicts with file from package filesystem-3.2-25.el7.x86_64
        file /usr/sbin from install of xen-4.15-unstable.x86_64 conflicts with file from package filesystem-3.2-25.el7.x86_64
[root@TestCloud1 xen]# rpm -e xen
warning: directory /boot: remove failed: Device or resource busy

After:

[root@TestCloud1 xen]# rpm -hiv dist/xen*rpm
Preparing...                          ################################# [100%]
Updating / installing...
   1:xen-4.15-unstable                ################################# [100%]
[root@TestCloud1 xen]# rpm -e xen
[root@TestCloud1 xen]#

Signed-off-by: Don Slutz <Don.Slutz@Gmail.com>
Acked-by: Wei Liu <wl@xen.org>