docs: infrastructure.rst: exclude device_link_state from device.h

This is already documented at device_link.rst, causing this
warning, due to a broken cross-reference:

.../Documentation/driver-api/device_link.rst: WARNING: Duplicate C declaration, also defined in 'driver-api/infrastructure'.
Declaration is 'device_link_state'.

Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

Documentation/driver-api/infrastructure.rst

···
 
 .. kernel-doc:: include/linux/device.h
    :internal:
+   :no-identifiers: device_link_state
 
 Device Drivers Base
 -------------------