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

This reverts commit 7d8f5ccc which is
commit d2c48b23 upstream.

It breaks the Android kernel abi, so revert it for now.  If it is needed
in the future it can be brought back in an ABI-safe way.

Bug: 161946584
Change-Id: I65e8ac1f57e138b38ba4e56a6595925e32029825
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>