build: fix meson binutils workaround

build: fix meson binutils workaround

The '-mno-avx512f' compiler flag is not passed to the compiler,
detection of the binutils and setting flags works fine, but the flag
itself not used by compiler.

Removing the interim 'march_opt' variable and using directly
'machine_args' and setting '-mno-avx512f' to 'machine_args'

Fixes: 566b4d7a968f ("build: fix meson check for binutils 2.30")
Cc: stable@dpdk.org
Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>