ARM: dts: qcom: mdm9615: remove invalid interrupt-names from pl18x mmc nodes

This solves the 'interrupt-names' was unexpected dtbs check error.

Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220928-mdm9615-dt-schema-fixes-v4-10-dac2dfaac703@linaro.org