sched/rt: Fix memory leak in rt_init()

sched/rt: Fix memory leak in rt_init()

c/s 2656bc7b0 "xen: adopt .deinit_pdata and improve timer handling"
introduced a error path into rt_init() which leaked prv if the
allocation of prv->repl_timer failed.

Introduce an error cleanup path.

Spotted by Coverity.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Meng Xu <mengxu@cis.upenn.edu>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
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CC: George Dunlap <george.dunlap@eu.citrix.com>
CC: Dario Faggioli <dario.faggioli@citrix.com>