rm_work.bbclass: ignore failure for removing pseudo folder

rm_work.bbclass: ignore failure for removing pseudo folder

When building over NFS2/3 server, removal of pseudo folders will fail in
some cases for there are files in it still used by pseudo daemon, thus
cause ".nfsXXXXX" files generated which can't be removed by clients. This
will lead rm_work task fo fail.

These failures could be safely ignored because ".nfsXXXXX" files would be
automatically cleared by NFS server when no clients keep opening them.

[YOCTO #4531]
[ CQID: WIND00412051 ]

(From OE-Core rev: 9742e866f545bc0d04aca697b541ed88f4e1764a)

Signed-off-by: Ming Liu <ming.liu@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>