This patch is an optimization in the bakery_lock_get() function
which removes the wfe() when waiting for other contenders to choose
their ticket i.e when their `entering` flag is set. Since the time
taken to execute bakery_get_ticket() by other contenders is bounded,
this wait is a bounded time wait. Hence the removal of wfe() and the
corresponding sev() and dsb() in bakery_get_ticket() may result
in better time performance during lock acquisition.

Change-Id: I141bb21294226b54cb6e89e7cac0175c553afd8d