devtools: fix ABI compatibility check
devtools: fix ABI compatibility check

The new default-taget "linux" is introduced in v19.05-rc1
but not exist in before release such as v19.02 which have
default-target "linuxapp", there is no compatibility report
when run validate-abi.sh to check ABI compatibility between
v19.05-rc1 and v19.02, changed default-target from "linux"
to "linuxapp" in validate-abi.sh

Fixes: 218c4e68c1d9 ("mk: use linux and freebsd in config names")
Cc: stable@dpdk.org

Signed-off-by: Peng Huang <f02ce4703401f984143d0c5f0c846807524456e9@intel.com>
Acked-by: Neil Horman <3316dc2d77df57653443c0391a5296176d6ca9c3@tuxdriver.com>
Acked-by: Bruce Richardson <66b9e8e8fbd5e9f41f91b0af050876182ce9d0e4@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk