Add support for ARV4518PW R01 and rename R01A.

There are two different versions of SMC7908A-ISP: R01 and R01A.
R01 has an internal clock for PCI, meanwhile R01A has an external clock.

This fixes: https://dev.openwrt.org/ticket/12884



Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

SVN-Revision: 35352