Clean up handling of checks for pending work by switching to the generic
infrastructure to do so.

We pick up handling for TIF_NOTIFY_RESUME from this switch, meaning that
task work will be correctly handled.
Signed-off-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210802192809.1851010-4-oupton@google.com