devtools: fix test of some build options

devtools: fix test of some build options

CONFIG_RTE_LIBRTE_PMD_ISAL was not tested because of a typo.

CONFIG_RTE_LIBRTE_PMD_QAT_SYM was not tested since it has been
introduced and made CONFIG_RTE_LIBRTE_PMD_QAT enabled by default.

While at it, DPDK_DEP_JSON is now checked for "y",
as other DPDK_DEP_* variables, instead of non-empty.

Fixes: 3c32e89f68e1 ("compress/isal: add skeleton ISA-L compression PMD")
Fixes: 7a34c2155716 ("compress/qat: add empty driver")
Cc: stable@dpdk.org
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Fiona Trahe <fiona.trahe@intel.com>