trace: fix C++ compilation
trace: fix C++ compilation

trace_mem is declared as 'void *' which triggers following error:
'...invalid conversion from ‘void*’ to ‘__rte_trace_header*’
[-fpermissive]...'

Fix this by adding proper typecast to 'struct __rte_trace_header *'.

Fixes: ebaee6409702 ("trace: simplify trace point headers")
Cc: stable@dpdk.org

Signed-off-by: Pawel Wodkowski <294d7c15cc176c94e055a67dba950949aac78018@gmail.com>
Signed-off-by: Sunil Kumar Kori <bdee174bc83e2fb76d979ba14c67b948a0d67de5@marvell.com>
Acked-by: Nicolas Chautru <5844138a49a7cd19205c4efe0c7b4bd431c6ad19@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk