LU-1311 Disable local irqs when locking tcds while walking them

LU-1311 Disable local irqs when locking tcds while walking them

This helps us to avoid a deadlock with other threads that goes like this:
thread doint the walking = (1)
other thread = (2)

(1) get some non-irq type tcd locked while walking the tcds
(2) get some irq/bh lock
(2) try to print a debugging message and block on the tcd lock held by (1)
(1) irq/bh arrives, tries to get irq/bh lock held by (2) == BAM!

Change-Id: If1e1cc57c0f2e287b453e34db0c894c1ca830b9a
Signed-off-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/2605
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Liang Zhen <liang@whamcloud.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>