workqueue: make deferrable delayed_work initializer names consistent

Initalizers for deferrable delayed_work are confused.

*
__DEFERRED_WORK_INITIALIZER()
* DECLARE_DEFERRED_WORK()
*
INIT_DELAYED_WORK_DEFERRABLE()

Rename them to

*
__DEFERRABLE_WORK_INITIALIZER()
* DECLARE_DEFERRABLE_WORK()
*
INIT_DEFERRABLE_WORK()

This patch doesn't cause any functional
changes.

Idea is taken here -
https://github.com/mrg666/android_kernel_mako/commit/612ffa9b133f57de28a19a682720d91e0424a9a4