fs/9p: Don't set stat.st_blocks based on nrpages

simple_getattr does set stat.st_blocks to a value
derived from nrpages. That is not correct with 9p

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>