powerpc/p1_p2_rdb_pc: print -PC suffix in board name

powerpc/p1_p2_rdb_pc: print -PC suffix in board name

Currently the -PC variants of the P1/P2 RDB boards do not print it on boot --
e.g. a P2020RDB-PC will claim to be a plain P2020RDB.  Besides being incorrect,
this can confuse a user into building U-Boot for P2020RDB rather than P2020RDB-PC,
resulting in a board that does not boot.

P1024RDB and P1025RDB are not included, as these boards apparently do not
have -PC as part of their name, even though they are supported by p1_p2_rdb_pc.

The P2020RDB variant covered by this is apparently P2020RDB-PCA rather
than P2020RDB-PC.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>