Linux: Fix lock ordering

Linux: Fix lock ordering

The inode mutex (or semaphore) should be held before acquiring the
alloc semaphore. Fix the lock ordering to avoid theoretical deadlocks.

Change-Id: Ifc572083dc92fff51be6785b0bcc92152fab1d73
Reviewed-on: http://gerrit.openafs.org/835
Reviewed-by: Marc Dionne <marc.c.dionne@gmail.com>
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit a2744cab12c87a8c42ba40a9f186a1f05c6886f8)
Reviewed-on: http://gerrit.openafs.org/977