Do not turn off AFS_HAVE_STATVFS for UKERNEL

Do not turn off AFS_HAVE_STATVFS for UKERNEL

Many param files turn off AFS_HAVE_STATVFS for UKERNEL. We obviously
still have statvfs() available whether we are running with UKERNEL or
not, so modify param files to enable it for UKERNEL if it was enabled
for non-UKERNEL.

The only places using this define are afsd and vol/partition.c, the
latter of which will not be affected.

Change-Id: I1f276c88cbe0ca401580a564be664a7fc6739fde
Reviewed-on: http://gerrit.openafs.org/1743
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>