timer: fix pointer to local outside scope

timer: fix pointer to local outside scope

A null array is allowed to be passed as one of the parameters to
rte_timer_alt_manage() as a convenience.  When that happened, an
anonymous array was created using compound literal syntax, and Coverity
detected that the object was out of scope in later uses of it. Create
an object in the proper scope instead.

Coverity issue: 337919
Fixes: c0749f7096c7 ("timer: allow management in shared memory")
Signed-off-by: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>