drm/i915: Fix typo in DRM_I915_OVERLAY_PUT_IMAGE ioctl define

Because of a typo, calling ioctl with DRM_IOCTL_I915_OVERLAY_PUT_IMAGE
is broken if the macro is used directly. When using libdrm the bug is
not hit, since libdrm handles the ioctl encoding internally.

The typo also leads to the .cmd and .cmd_drv fields of the drm_ioctl
structure for DRM_I915_OVERLAY_PUT_IMAGE having inconsistent content.

Signed-off-by: Ole Henrik Jahren <olehenja@alumni.ntnu.no>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@kernel.org
Signed-off-by: Keith Packard <keithp@keithp.com>