Staging: ste_rmi4: Use SIMPLE_DEV_PM_OPS() macro

Macro SIMPLE_DEV_PM_OPS() can be used when same suspend
and resume callbacks are used for suspend to RAM and
hibernation. So, here use SIMPLE_DEV_PM_OPS to make code
shorter and cleaner.

Signed-off-by: Vaishali Thakkar <vthakkar1994@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>