Makefile: qemu-bundle is a directory

Makefile: qemu-bundle is a directory

So make distclean should remove it with -rf, not -f alone.

It has been that way since it was included.

ommit cf60ccc3306ca4726cbd286a156863863b00ff4f
Author: Akihiko Odaki <akihiko.odaki@gmail.com>
Date:   Fri Jun 24 23:50:37 2022 +0900

    cutils: Introduce bundle mechanism

Fixes: cf60ccc3306ca4726cbd286a156863863b00ff4f
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-Id: <20230301111910.1660-1-quintela@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>