app/testpmd: fix parsing RSS queue rule

app/testpmd: fix parsing RSS queue rule

Declare a local variable 'arg' to hold the pointer to ARGS_ENTRY_ARB,
otherwise, the pop 'arg' in 'parse_int' holds wrong data like 'arg->
offset = 5912737, arg->size = 0', this caused the parse failure.

If calling like 'push_args(ctx, ARGS_ENTRY_ARB..)', the below code for
assigning 'offset & size' will be missed for some gcc optimization.

parse_vc_action_rss_queue
    29c5:	c5 f9 ef c0          	vpxor  %xmm0,%xmm0,%xmm0
    29c9:	43 8d 44 24 68       	lea    0x68(%r12,%r12,1),%eax
    29ce:	48 c7 44 24 20 00 00 	movq   $0x0,0x20(%rsp)
    29d5:	00 00
    29d7:	c5 f8 29 44 24 10    	vmovaps %xmm0,0x10(%rsp)
    29dd:	89 44 24 18          	mov    %eax,0x18(%rsp)
    29e1:	48 63 83 0c 01 00 00 	movslq 0x10c(%rbx),%rax
    29e8:	c7 44 24 1c 02 00 00 	movl   $0x2,0x1c(%rsp)
    29ef:	00
    29f0:	c5 f8 29 04 24       	vmovaps %xmm0,(%rsp)

The above assembly code is from this modification with:
    gcc version 9.1.1 20190503 (Red Hat 9.1.1-1) (GCC)
    Fedora release 30 (Thirty)
    5.1.11-300.fc30.x86_64

Fixes: d0ad8648b1c5 ("app/testpmd: fix RSS flow action configuration")
Cc: stable@dpdk.org
Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
Reviewed-by: Xiaolong Ye <xiaolong.ye@intel.com>
Acked-by: Bernard Iremonger <bernard.iremonger@intel.com>