drm/i915/hdmi: move declarations for hsw_read/write_infoframe() to the right place

The functions are located in intel_hdmi.c, put the declarations in
intel_hdmi.h.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/e8cd28a3c46f06b9654df8b7990e1e6a1d9e18c1.1738677489.git.jani.nikula@intel.com


Signed-off-by: Jani Nikula <jani.nikula@intel.com>