Handle rounding up nfsv3 handle size to multiple of 4 bytes in nfs3_sizeof_handle

Doing this here means everyone who uses nfs3_sizeof_handle get's the
right wire size of the handle.

Signed-off-by: Frank S. Filz <ffilz@us.ibm.com>
Signed-off-by: Venkateswararao Jujjuri (JV) <jvrao@linux.vnet.ibm.com>
Added tag 3.3.3_rev1

Signed-off-by: Venkateswararao Jujjuri "<jvrao@linux.vnet.ibm.com>