rockchip: rk35xx: Enable eMMC HS200 mode by default

Testing has shown that writing to eMMC using a slower mode then HS200
typically generate an ERROR on first attempt on RK3588.

  # Rescan using MMC legacy mode
  => mmc rescan 0

  # Write a single block to sector 0x4000 fails with ERROR
  => mmc write 20000000 4000 1

  # Write a single block to sector 0x4000 now works
  => mmc write 20000000 4000 1

With the MMC_SPEED_MODE_SET Kconfig option enabled.

Writing to eMMC using HS200 mode work more reliably than slower modes on
RK35xx boards. Enable MMC_HS200_SUPPORT Kconfig option by default to
prefer use of HS200 mode on RK356x and RK3588.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>