[U-Boot] initramfs support through the initrd mechanism of u-boot

Currently the support of Linux initial file system by u-boot is a file system image through "initrd". I tweaked a little of both the "lib_arm/armlinux.c" and the initramfs of Linux (a gziped cpio) so that the initramfs file could be passed to the kernel. For example: bootm c0008000 c1008000 will pass c1008000 to kernel as the start address of a initramfs.

However in the Linux kernel it seems that it expects a physical address of initrd start, but u-boot passes a virtual address if MMU is enable. So a "virt_to_phy" should be used on the address before it is passed to the kernel.

I'm currently using a Mini6410 (with Samsung S3C6410 CPU), an ARM board from China.

Thanks, Thomas