dma/idxd: fix non-AVX builds with old compilers

dma/idxd: fix non-AVX builds with old compilers

When building without AVX2 support using an older compiler e.g. gcc 4.8
on Centos/RHEL 7, we get build errors due to the use of AVX2 intrinsics.
This is because the compiler does not support
"__attribute__((target(AVX2)))" function attribute. Disable build of
this driver such edge cases.

Generic builds using recent compilers, and all builds with a minimum
baseline of AVX2 are unaffected by this change.

Fixes: aa802b10237c ("dma/idxd: fix AVX2 in non-datapath functions")
Cc: stable@dpdk.org
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Tested-by: Yu Jiang <yux.jiang@intel.com>