drm: fix DRM_DISPLAY_DP_HELPER dependencies, part 2

After my fix yesterday, I ran into another problem of the same kind:

aarch64-linux-ld: drivers/gpu/drm/bridge/analogix/analogix_dp_core.o: in function `drm_dp_dpcd_readb':
analogix_dp_core.c:(.text+0x194): undefined reference to `drm_dp_dpcd_read'
aarch64-linux-ld: drivers/gpu/drm/bridge/analogix/analogix_dp_core.o: in function `drm_dp_dpcd_writeb':
analogix_dp_core.c:(.text+0x214): undefined reference to `drm_dp_dpcd_write'
aarch64-linux-ld: drivers/gpu/drm/bridge/analogix/analogix_dp_core.o: in function `analogix_dp_stop_crc':
analogix_dp_core.c:(.text+0x4b0): undefined reference to `drm_dp_stop_crc'
aarch64-linux-ld: drivers/gpu/drm/bridge/analogix/analogix_dp_core.o: in function `analogix_dp_start_crc':
analogix_dp_core.c:(.text+0xbe8): undefined reference to `drm_dp_start_crc'

Add the same dependency again to ROCKCHIP_ANALOGIX_DP after checking that
nothing else selects the analogix driver. Also add a dependency to
DRM_ANALOGIX_DP to make it easier to identifier future problems of
this type when they get introduced.

Fixes: 0323287d ("drm: Switch DRM_DISPLAY_DP_HELPER to depends on")
Fixes: d1ef8fc1 ("drm: fix DRM_DISPLAY_DP_HELPER dependencies")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240405143531.925589-1-arnd@kernel.org