'Flexible client buffer growth' fallout

'Flexible client buffer growth' fallout

e7c966354c428a5a5929a3db6a829ee71c8ba2fc re-introduced a usage of the
'M' lock macro variants previously removed by
bab6fd227f5724c4e4ca5d0ba1dc64e21ed21f97. Use the non-'M' macros
instead so we can build.

Change-Id: Ie27fb8e82a7440a6952517d9a0cc1aeb8523511c
Reviewed-on: http://gerrit.openafs.org/872
Tested-by: Andrew Deason <adeason@sinenomine.net>
Tested-by: Marc Dionne <marc.c.dionne@gmail.com>
Reviewed-by: Marc Dionne <marc.c.dionne@gmail.com>
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>