mmc: rockchip_sdhci: Disable DMA mode using a device tree property

Loading part of TF-A into SRAM from eMMC using DMA fails on RK3399
similar to other Rockchip SoCs. Checksum validation fails with:

  ## Checking hash(es) for Image atf-2 ... sha256 error!
  Bad hash value for 'hash' hash node in 'atf-2' image node
  spl_load_simple_fit: can't load image loadables index 1 (ret = -1)
  mmc_load_image_raw_sector: mmc block read error
  SPL: failed to boot from all boot devices
  ### ERROR ### Please RESET the board ###

Add a device tree property, u-boot,spl-fifo-mode, to control when the
rockchip_sdhci driver should disable the use of DMA and fallback on PIO
mode. Same device tree property is used by the rockchip_dw_mmc driver.

In commit 2cc6cde6 ("mmc: rockchip_sdhci: Limit number of blocks
read in a single command") the DMA mode was disabled using a CONFIG
option on RK3588. Revert that and instead disable DMA using the device
tree property for all RK3588 boards, also apply similar workaround for
all RK3399 boards.

Fixes: 2cc6cde6 ("mmc: rockchip_sdhci: Limit number of blocks read in a single command")
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Quentin Schulz <foss+uboot@0leil.net> # RK3399 Puma, RK3588 Tiger