ARM: sh-mobile: Use of_cpu_node_to_id() to read CPU node 'reg'

ARM: sh-mobile: Use of_cpu_node_to_id() to read CPU node 'reg'

Replace open coded CPU nodes reading of "reg" and translation to logical
ID with of_cpu_node_to_id().

The original code called of_parse_phandle() CONFIG_NR_CPUS times
regardless of the length of 'cpus'. Optimize the loop to bail out once
of_parse_phandle() fails as the end of 'cpus' property has been reached.

Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230327205228.573456-1-robh@kernel.org
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>