drm: atmel_hlcdc: replace regmap_read with regmap_read_poll_timeout

Replace regmap_read with regmap_read_poll_timeout to neatly handle
retries

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
Acked-by: Dharma Balasubiramani <dharma.b@microchip.com>
Reviewed-by: Hari Prasath Gujulan Elango <hari.prasathge@microchip.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240424053351.589830-4-manikandan.m@microchip.com