Revert "firmware: arm_sdei: Fix sleep from invalid context BUG"

This reverts commit 48ac727e.

It is not needed in Android systems, and it breaks the ABI for no real
reason, so revert it.

Bug: 161946584
Change-Id: I0ee2f63bbf65ff04dea4434438e4ece97406f7a1
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>