Use correct spelling of "U-Boot"

Correct spelling of "U-Boot" shall be used in all written text
(documentation, comments in source files etc.).

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Minkyu Kang <mk7.kang@samsung.com>

powerpc/mpc85xx: Rewrite spin table to comply with ePAPR v1.1

Move spin table to cached memory to comply with ePAPR v1.1.
Load R3 with 64-bit value if CONFIG_SYS_PPC64 is defined.

'M' bit is set for DDR TLB to maintain cache coherence.

See details in doc/README.mpc85xx-spin-table.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>