[fs/9p] Make access=client default in 9p2000.L protocol

Current code sets access=user as default for all protocol versions.
This patch chagnes it to "client" only for dotl.

User can always specify particular access mode with -o access= option.
No change there.

Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>