kbd: make libkbdfile-test08 ptest work for multilib

kbd: make libkbdfile-test08 ptest work for multilib

This patch fixes kbd ptest libkbdfile-test08 failure in 64-bit images.

```sh
root@intel-x86-64:/usr/lib64/kbd/ptest# ./run-ptest
make: Entering directory '/usr/lib64/kbd/ptest/tests'
make[1]: Entering directory '/usr/lib64/kbd/ptest/tests'
PASS: libkbdfile-test01
PASS: libkbdfile-test02
PASS: libkbdfile-test03
PASS: libkbdfile-test04
PASS: libkbdfile-test05
PASS: libkbdfile-test06
PASS: libkbdfile-test07
FAIL: libkbdfile-test08
PASS: libkbdfile-test09
...
```

`DATADIR` and `ABS_DATADIR` are compile flags defined in
./kbd/tests/Makefile.am. `DATADIR` is the relative directory of
kbd, i.e `./kbd/ptest/tests` whereas `ABS_DATADIR` is the full
directory path, i.e `/usr/lib/kbd/ptest/tests`. The latter has a
problem when building ptests for a 64-bit image, because the tests
folder is located at `/usr/lib64/kbd/ptest/tests` instead.

Therefore `ABS_DATADIR` is changed to `DATADIR`, also consistent with
what *every other* kbd test is doing.

The test searches DATADIR recursively for a file named `test0.map`,
but it finds the wrong file at
    `/findfile/test_0/keymaps/test0.map`,
while it actually needs
    `/findfile/test_0/keymaps/i386/qwerty/test0.map`.

Thus appending `/i386` to `dirpath` so that `libkbdfile-test08.c`
    finds the right test file.

Signed-off-by: Matthew Zeng<Matthew.Zeng@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>