arm64: defconfig: mediatek: enable PHY drivers

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 924d66011f24 ("drm/mediatek: stop selecting foreign drivers")
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

Fixes: 924d66011f24 ("drm/mediatek: stop selecting foreign drivers")
Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Vignesh Raman <vignesh.raman@collabora.com>
Link: https://lore.kernel.org/r/20250512131933.1247830-1-vignesh.raman@collabora.com
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>