of/address: Fix variable name in comment of of_iomap

The first variable name of of_iomap is np while previous
comment write device here.
Signed-off-by: Wenchao Hao <haowenchao22@gmail.com>
Link: https://lore.kernel.org/r/20200701162444.9494-1-haowenchao22@gmail.comSigned-off-by: Rob Herring <robh@kernel.org>

drivers/of/address.c

@@ -864,7 +864,7 @@ EXPORT_SYMBOL_GPL(of_address_to_resource);
 
 /**
  * of_iomap - Maps the memory mapped IO for a given device_node
- * @device:	the device whose io range will be mapped
+ * @np:		the device whose io range will be mapped
  * @index:	index of the io range
  *
  * Returns a pointer to the mapped memory