EX-8245 ptlrpc: always do vmalloc

EX-8245 ptlrpc: always do vmalloc

If we were ever to do an allocation with kmalloc, we could
get non-page aligned memory.  So just use vmalloc directly.

Sadly, this isn't the problem with infiniband.  We never
ask for < 8192, which is the libcfs kmalloc/vmalloc cutoff.

Still, this is a timebomb if we ever changed the libcfs
kmalloc/vmalloc cutoff, so, fix it.

Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: Id20898065b516d363d9dc280e71be1b5cfb6f4a7
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/52532
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>