drm: bridge: dw_hdmi: Audio: fix returnvar.cocci warnings

drivers/gpu/drm/bridge/synopsys/dw-hdmi-gp-audio.c:80:5-8: Unneeded variable: "ret". Return "0" on line 94
drivers/gpu/drm/bridge/synopsys/dw-hdmi-gp-audio.c:105:5-8: Unneeded variable: "ret". Return "0" on line 112

 Remove unneeded variable used to store return value.

Generated by: scripts/coccinelle/misc/returnvar.cocci

CC: Sandor Yu <Sandor.yu@nxp.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: kernel test robot <lkp@intel.com>
Reviewed-by: Sandor Yu <Sandor.yu@nxp.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/YmFzutFV/iDyEQF2@dd18de969aa6