arm64: dts: qcom: sm6125-seine: Lock eMMC and SD Card IDs via aliases

Ensure the eMMC and SD Card always have a predictable slot index by
predetermining them via aliases.

Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221222203636.250190-6-marijn.suijten@somainline.org