I've changed load address of initrd from 0x4600 to 0x4100 in
boot.scr and now SD cards seems to work ok, it's recognized by kernel as
was with older kernel.
I have one (or two) more question regarding those addresses. Which address
ranges are legal anyway for u-boot (placed in boot.scr)
Unfortunately, currently I don't have time for bisecting.
One thing that I forgot to mention is that I made initrd image with
'mkimage' option '-a 0x4500', if it means anything to you.
Another thing which I would mention is example from sunxi initial ramdisk
wiki:
fatload mmc 0 0x4300 sc
