arm64: dts: hikey: Revert "Enable HS200 mode on eMMC"

This reverts commit abd7d097. This
change was already partially reverted by John Stultz in
commit 9c6d26df

 ("arm64: dts: hikey: Fix eMMC corruption regression").

This change appears to cause controller resets and block read failures
which prevents successful booting on some hikey boards.

Cc: Ryan Grachek <ryan@edited.us>
Cc: Wei Xu <xuwei5@hisilicon.com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: devicetree@vger.kernel.org
Cc: stable <stable@vger.kernel.org> #4.17+
Signed-off-by: Alistair Strachan <astrachan@google.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>