HID: rmi: Check that the device is a RMI device in suspend and resume callbacks

Commit 09256360 ("HID: rmi: Disable scanning if the device is not a wake
source") introduced a regression for devices which use hid-rmi to handle
composite USB devices. The suspend or resume callbacks are not checking
that the device is a RMI device before calling rmi_read or rmi_write.
This results in dereferencing uninitialized variables on non RMI devices. This
patch checks that the RMI_DEVICE flag is set before sending RMI commands to the
device.

Reported-by: Rodrigo Gomes <rodrigo.toste.gomes@gmail.com>
Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>