MIPS: Sibyte: drop select of SIBYTE_CFE

SIBYTE_CFE got killed in commit 05f94eeb ("MIPS: Sibyte: Remove
standalone kernel support"). This means that since v2.6.31 there is no
Kconfig symbol SIBYTE_CFE. The select statement for that symbol is a
nop. Drop it.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>