Fix OsTest#test_xattr_Errno test on CTS

Since 4.9 kernel (6c6ef9f26e598fb977f60935e109cd5b266c941a), the mechanism
for calling xattr inode operations has changed. These changes led to the
incorrectness of the conditions checked in the test. This patch take into
account the aforementioned changes - softed the requirements for the
returned error codes and do not take into account the conditions under
which the test was performed (kernel version, user privileges).
Complementary to 52056d7b patch.

Test: libcore.io.OsTest
Change-Id: Ie74a8c5b8b9b60e6c60b69ed744c419c03f904aa