net/igc: fix build with gcc optimization level 0

net/igc: fix build with gcc optimization level 0

GCC build with '-O0' failed for:
 ../drivers/net/igc/base/igc_api.c
 Assembler messages:
29: Error: selected processor does not support `casp x0,x1,x2,x3,[x4]'
82: Error: selected processor does not support `caspa x0,x1,x2,x3,[x4]'
135: Error: selected processor does not support `caspl x0,x1,x2,x3,[x4]'
188: Error: selected processor does not support `caspal x0,x1,x2,x3,[x4]'

This is due to c_args not been passed to meson.

Fixes: 8cb7c57d9b3c ("net/igc: support device initialization")
Cc: stable@dpdk.org
Reported-by: Feifei Wang <feifei.wang2@arm.com>
Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
Tested-by: Jerin Jacob <jerinj@marvell.com>
Acked-by: Haiyue Wang <haiyue.wang@intel.com>