The special case when wic is set up to use SD/MMC-Cards in place
of sdX disks is not handled properly.
Append 'p' to the rootdev when disk is SD/MMC-Cards fix this situation.
(From OE-Core rev: 3a95c4549f743aa47456c76e687a863c64c7a7f4)
Signed-off-by: João Henrique Ferreira de Freitas <joaohf@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>