arm64: defconfig: mediatek: enable PHY drivers

The mediatek display driver fails to probe on mt8173-elm-hana and
mt8183-kukui-jacuzzi-juniper-sku16 in v6.14-rc4 due to missing PHY
configurations.

Commit [1] stopped selecting the MediaTek PHY drivers, requiring them
to be explicitly enabled in defconfig.

Enable the following PHY drivers for MediaTek platforms:
- CONFIG_PHY_MTK_HDMI=m for HDMI display
- CONFIG_PHY_MTK_MIPI_DSI=m for DSI display
- CONFIG_PHY_MTK_DP=m for DP display

[1] commit 924d6601 ("drm/mediatek: stop selecting foreign drivers")

Fixes: 924d6601 ("drm/mediatek: stop selecting foreign drivers")
Signed-off-by: Vignesh Raman <vignesh.raman@collabora.com>
Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>