The 601 processor will generate an alignment exception for accesses
which cross a page boundary.  In the boot wrapper code, OF is still
handling all exceptions, and it doesn't have an alignment exception
handler that emulates the instruction and continues.

This changes the memcpy and memmove routines in the boot wrapper to
avoid doing unaligned accesses.  If the source and destination are
misaligned with respect to each other, we just copy one byte at a
time.

Signed-off-by: Paul Mackerras <paulus@samba.org>

This also extends the code to handle 32-bit ELF vmlinux files as well
as 64-bit ones.  This is sufficient for booting on new-world 32-bit
powermacs (i.e. all recent machines).

Signed-off-by: Paul Mackerras <paulus@samba.org>