zebra: Fix wrong variable used in `for` loop

zebra: Fix wrong variable used in `for` loop

The `for` loop starting at line 1848 searches the `func_allocated` array
for a pointer that points to a specific `sid_wide_func` element.

The loop should iterate over all the elements of the `func_allocated`
array and dereference each element to see if it is the one we are
looking for.

Currently, the loop is using the wrong variable to iterate over the
array.

Let's fix this issue by using the correct variable in the loop.

Fixes CID 1594014
Fixes CID 1594016

** CID 1594014:  Null pointer dereferences  (FORWARD_NULL)
/zebra/zebra_srv6.c: 1860 in release_srv6_sid_func_explicit()

________________________________________________________________________________________________________
*** CID 1594014:  Null pointer dereferences  (FORWARD_NULL)
/zebra/zebra_srv6.c: 1860 in release_srv6_sid_func_explicit()
1854
1855     				/* Lookup SID function in the functions allocated list of EWLIB range */
1856     				for (ALL_LIST_ELEMENTS_RO(block->u.usid
1857     								  .wide_lib[sid_func]
1858     								  .func_allocated,
1859     							  node, sid_func_ptr))
     CID 1594014:  Null pointer dereferences  (FORWARD_NULL)
     Dereferencing null pointer "sid_wide_func_ptr".
1860     					if (*sid_wide_func_ptr == sid_wide_func)
1861     						break;
1862
1863     				/* Ensure that the SID function is allocated */
1864     				if (!sid_wide_func_ptr) {
1865     					zlog_warn("%s: failed to release wide SID function %u, function is not allocated",

** CID 1594016:  Possible Control flow issues  (DEADCODE)
/zebra/zebra_srv6.c: 1871 in release_srv6_sid_func_explicit()

________________________________________________________________________________________________________
*** CID 1594016:  Possible Control flow issues  (DEADCODE)
/zebra/zebra_srv6.c: 1871 in release_srv6_sid_func_explicit()
1865     					zlog_warn("%s: failed to release wide SID function %u, function is not allocated",
1866     						  __func__, sid_wide_func);
1867     					return -1;
1868     				}
1869
1870     				/* Release the SID function from the EWLIB range */
     CID 1594016:  Possible Control flow issues  (DEADCODE)
     Execution cannot reach this statement: "listnode_delete(block->u.us...".
1871     				listnode_delete(block->u.usid.wide_lib[sid_func]
1872     							.func_allocated,
1873     						sid_wide_func_ptr);
1874     				zebra_srv6_sid_func_free(sid_wide_func_ptr);
1875     			} else {
1876     				zlog_warn("%s: function %u is outside ELIB [%u/%u] and EWLIB alloc ranges [%u/%u]",

Signed-off-by: Carmine Scarpitta <cscarpit@cisco.com>