When the boardrev with a prefix is not available, try to read it
without a prefix. This is based on code from the Broadcom SDK.
Signed-off-by: NHauke Mehrtens <hauke@hauke-m.de>
Acked-by: NRalf Baechle <ralf@linux-mips.org>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>