iosys-map: Fix typo in documentation

It's one argument, vaddr_iomem, not 2 (vaddr and _iomem).
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220610232130.2865479-3-lucas.demarchi@intel.com

include/linux/iosys-map.h

@@ -23,7 +23,7 @@
  *	memcpy(vaddr, src, len);
  *
  *	void *vaddr_iomem = ...; // pointer to I/O memory
- *	memcpy_toio(vaddr, _iomem, src, len);
+ *	memcpy_toio(vaddr_iomem, src, len);
  *
  * The user of such pointer may not have information about the mapping of that
  * region or may want to have a single code path to handle operations on that