Revert "tracing: Fix sleeping while atomic in kdb ftdump"

This reverts commit 426656e8 which is
commit 495fcec8 upstream.

It breaks the Android kernel abi, and is not needed for any Android
devices at this time.  If it is needed in the future, it can be brought
back in an abi-safe way.

Bug: 161946584
Change-Id: Iafb5d7fa1dd6f80b941f28a2b9e6d56adc6ceb17
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>