lmb: Add the Rockchip architecture as requiring DMA below 4G

Loading EFI parts like a Debian-Installer on Rockchip SoCs creates
interesting results, in that on some boards the Grub bootloader can't
find any partitions on a USB-Stick, or loading a kernel from Grub spews
    EHCI fail timeout STS_IAA set
messages before failing and on others the loading something like efivars
from an eMMC creates read errors and making the MMC vanish from U-Boot.

This only affected boards with at least 4GB of RAM.

These boards have at least 256MB of memory placed above the actual 4GB
address space (due to the iomem being in between) and while kernel,
initramfs, dt are generally loaded to predefined addresses, additional
EFI parts (efivars, etc) are likely just loaded "somewhere" and it seems
this always landed in that higher up memory part.

Also in the Linux-kernel peripherals like EMMC, USB, etc already run
with a 32bit dma-mask set.

So far, I've seen this on RK3568 and RK3588, but as the same peripherals
are used on most Rockchip SoCs, it makes sense to limit this on all.

So add ARCH_ROCKCHIP to the default-y list of LMB_LIMIT_DMA_BELOW_RAM_TOP.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Peter Robinson <pbrobinson@gmail.com>

lib/Kconfig

@@ -1298,7 +1298,7 @@ config SPL_LMB_ARCH_MEM_MAP
 config LMB_LIMIT_DMA_BELOW_RAM_TOP
 	bool
 	depends on LMB
-	default y if ARCH_BCM283X
+	default y if ARCH_BCM283X || ARCH_ROCKCHIP
 	help
 	  Some architectures can not DMA above ram_top boundary,
 	  which is after 4 GiB or 32-bit boundary too. Limit the