ARM: dts: qcom: Fix sdhci node names - use 'mmc@'

Since the Qualcomm sdhci-msm device-tree binding has been converted
to yaml format, 'make dtbs_check' reports issues with
inconsistent 'sdhci@' convention used for specifying the
sdhci nodes. The generic mmc bindings expect 'mmc@' format
instead.

Fix the same.

Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Bhupesh Sharma <bhupesh.sharma@linaro.org>
[bjorn: Extracted from combined arm64 patch]
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220514215424.1007718-2-bhupesh.sharma@linaro.org