ARM: dts: qcom: msm8974-FP2: Add mmc* aliases

Add aliases for internal storage and SD card so they don't randomly
switch around.

Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220421211936.345168-2-luca@z3ntu.xyz