mountd: Plug v4root memory leak

Valgrind reports that the memory allocated for eep's e_hostname field
was not being freed.  eep is not visible outside of v4root_create(),
so we don't need to strdup() that string.

Introduced by commit 3b777b0 "exports: NFSv4 pseudoroot support
routines" (Dec 1, 2009).

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>