test: fix build

test: fix build

With "make -C test/" command getting following warnings:
 awk: cmd. line:1: fatal: cannot open file `/cmdline_test/cmdline_test/'
      for reading (No such file or directory)
 awk: cmd. line:1: fatal: cannot open file
      `/test-pipeline/test-pipeline/' for reading (No such file or
      directory)
 awk: cmd. line:1: fatal: cannot open file `/test-acl/test-acl/'
      for reading (No such file or directory)

This is because unexpected/invalid MAPFILE param passed to
check-experimental-syms.sh

There is no easy way to unify MAPFILE for different build options,
instead add an input verification to script, and silently ignore wrong
values.

Fixes: a6ec31597a0b ("mk: add experimental tag check")
Cc: stable@dpdk.org
Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>