Remove CONFIG_BOARDNAME and CONFIG_BOARD_NAME

Both of these variables are used in a few hard-coded ways to set some
string values or print something to the user.  In almost all cases, it's
just as useful to hard-code the value used.  The exception here is
printing something closer to correct board name for p1_p2_rdb machines.
This can be done using something from the device tree, but for now
hard-code a non-CONFIG based value instead.

Signed-off-by: Tom Rini <trini@konsulko.com>