drivers: allow build with VLAs

The drivers nfb, mvpp2 and mvsam use some variable length arrays
in their code, so the warnings about VLA must be disabled for now,
until removal for MSVC support, as in some other drivers.

The warnings look like below:

nfb_rx.h:156:16: error:
	ISO C90 forbids variable length array 'packets' [-Werror=vla]
  156 |         struct ndp_packet packets[nb_pkts];

mvpp2/mrvl_flow.c:108:9: error:
     ISO C90 forbids variable length array 'zeros' [-Werror=vla]
  108 |         uint8_t zeros[size];

mvsam/rte_mrvl_pmd.c:865:16: error:
	ISO C90 forbids variable length array 'requests_crp' [-Werror=vla]
  865 |         struct sam_cio_op_params requests_crp[nb_ops];

Fixes: 1bf8680 ("build: warn on uses of VLA")

Signed-off-by: Thomas Monjalon <[email protected]>

drivers/crypto/mvsam/meson.build

@@ -20,4 +20,6 @@ ext_deps += dep
 
 sources = files('rte_mrvl_pmd.c', 'rte_mrvl_pmd_ops.c')
 
+cflags += no_wvla_cflag
+
 deps += ['bus_vdev', 'common_mvep', 'security']

drivers/net/mvpp2/meson.build

@@ -26,4 +26,6 @@ sources = files(
         'mrvl_tm.c',
 )
 
+cflags += no_wvla_cflag
+
 deps += ['cfgfile', 'common_mvep']

drivers/net/nfb/meson.build

@@ -21,3 +21,5 @@ sources = files(
         'nfb_stats.c',
         'nfb_tx.c',
 )
+
+cflags += no_wvla_cflag