drm/bridge: Fix returned array size name for atomic_get_input_bus_fmts kdoc

The returned array size for input formats is set through
atomic_get_input_bus_fmts()'s 'num_input_fmts' argument, so use
'num_input_fmts' to represent the array size in the function's kdoc,
not 'num_output_fmts'.

Fixes: 91ea8330 ("drm/bridge: Fix the bridge kernel doc")
Fixes: f32df58a ("drm/bridge: Add the necessary bits to support bus format negotiation")
Signed-off-by: Liu Ying <victor.liu@nxp.com>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230314055035.3731179-1-victor.liu@nxp.com