microblaze: Do not use r6 in head.S

r6 stores pointer to ramdisk and shouldn't
be used before it is passed to machine_early_init.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
microblaze: Fix free_init_pages function

- fce() is used only in init.c file - let's use static
- start and end addresses should be page align
- remove additional addr variable
- use pr_info instead of printk(KERN_INFO...)
- use __free_page(page) instead of free_page(start)
  it is faster because of no checking,
  if ramdisk is out of the kernel you will get kernel panic anyway

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
microblaze: Fix initrd support

Initrd/ramdisk support has been never validated.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
microblaze: Do not select OPT_LIB_ASM by default

This option is valid only for BE systems.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>