powerpc: Drop unreferenced CONFIG_* defines

powerpc: Drop unreferenced CONFIG_* defines

The following config symbols are only defined once and never referenced
anywhere else:

CONFIG_CYRUS
CONFIG_IDS8313
CONFIG_MPC8308_P1M
CONFIG_MPC8308RDB
CONFIG_MPC8349EMDS
CONFIG_MPC8349ITXGP
CONFIG_SBC8349
CONFIG_SBC8548
CONFIG_SBC8641D
CONFIG_TQM834X
CONFIG_VE8313
CONFIG_XPEDITE5140
CONFIG_XPEDITE5200
CONFIG_XPEDITE550X

Most of them are config symbols named after the respective boards which
seems to have been a standard practice at some point.

Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
Acked-by: Mario Six <mario.six@gdsys.cc>