ARM: dts: qcom: msm8974-klte: Fix shdc numbering

Since commit fa2d0aa9

 ("mmc: core: Allow setting slot index
via device tree alias") proper aliases should be named "mmcN".

Signed-off-by: Alexey Minnekhanov <alexeymin@postmarketos.org>
Link: https://lore.kernel.org/r/20210110185835.133059-1-alexeymin@postmarketos.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>