lavu/opt: Fix return of uninitialised value

In one of the failure paths of av_opt_get_array, the ret variable
was accidentally declared again, shadowing the outer one and once when
jumping to the fail label would return the still uninitialised outer
one.

To fix this simply remove the local declaration of ret that shadowed
the outer one.

Introduced in d89930f866

Fixes: CID1618663 Uninitialized scalar variable

libavutil/opt.c

@@ -2214,7 +2214,6 @@ int av_opt_get_array(void *obj, const char *name, int search_flags,
             double     num = 1.0;
             int        den = 1;
             int64_t intnum = 1;
-            int ret;
 
             ret = read_number(o, src, &num, &den, &intnum);
             if (ret < 0)