Remove spieval board support

Recent changes caused that the spieval board now is included in the
boards built by MAKEALL, which revealed that compilation for this
board has been broken for a long time:

mpc5xxx_fec.c:899:2: error: #error fec->xcv_type not initialized.
mpc5xxx_fec.c:899:2: error: #error fec->xcv_type not initialized.

The board is orphaned.  Drop support for it.

Signed-off-by: Wolfgang Denk <wd@denx.de>

boards.cfg

@@ -104,7 +104,6 @@ uc101		powerpc	mpc5xxx
 v38b		powerpc	mpc5xxx
 pf5200		powerpc	mpc5xxx		-		esd
 aev		powerpc	mpc5xxx		tqm5200		tqc
-spieval		powerpc	mpc5xxx		tqm5200		tqc
 sorcery		powerpc	mpc8220
 A3000		powerpc	mpc824x		a3000
 barco		powerpc	mpc824x