arm64: dts: qcom: Fix SD card vqmmc max voltage on sc7180-trogdor

It never makes sense to set the IO voltage of the SD card (vqmmc) to a
voltage that's higher than the voltage of the card's main power supply
(vmmc).  The card's main voltage is 2.952V on trogdor, so let's set
the max for the IO voltage to the same.

NOTE: On Linux, this is pretty much a no-op currently.  Linux already
makes an effort to match vqmmc with vmmc when running at "3.3" signal
voltage, so both before and after this change we end up running vqmmc
at 2.904V when talking to non-UHS cards.  It still seems cleaner to
make it a little more correct, though.

Also note: as per above, on Linux right now we end up running vqmmc as
2.904V even though vmmc is 2.952V.  This isn't super ideal but
shouldn't really hurt.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20201204104900.1.I0a4ac2c7f4d405431cf95eb7b7c36800660516ec@changeid
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>