clocksource/drivers/timer-ti-dm: Drop unnecessary restore

The device is not losing context on CPU_CLUSTER_PM_ERROR. As we are only
saving and restoring context with cpu_pm, there is no need to restore the
context in case of an error.

Note that the unnecessary restoring of context does not cause issues, it's
just not needed.

Cc: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210518075306.35532-1-tony@atomide.com