sh: fix se7724 ceu names

Use "ceu0" and "ceu1" as CEU names instead of "ceu".
This fixes "memchunk" kernel command line selection
on the solution engine 7724 board.

With this patch applied use "memchunk.ceu0=1m" or
"memchunk.ceu1=1m" on kernel command line to override
physically memory size to one meg for CEU0 or CEU1.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>