Revert "sunrpc: move the close processing after do recvfrom method"

This reverts commit b0401d725334a94d57335790b8ac2404144748ee, which
moved svc_delete_xprt() outside of XPT_BUSY, and allowed it to be called
after svc_xpt_recived(), removing its last reference and destroying it
after it had already been queued for future processing.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>