OMAP: DSS2: HDMI: remove error prints in check_timings

check_timings() is supposed to be used to verify if timings are ok or
not. Currently the HDMI driver prints error messages if the timings are
not ok. This is not right, as it is no error to give invalid timings to
check_timings().

Remove the error prints.

Cc: Mythri P K <mythripk@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>