drm/panel: nt35510: fix typo

Replace 'HFP' with 'HBP'.

Fixes: 899f24ed ("drm/panel: Add driver for Novatek NT35510-based panels")
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231023090613.1694133-1-dario.binacchi@amarulasolutions.com