MIPS: Move Inca-IP targets to boards.cfg

At the same time, fix up CPU_CLOCK_RATE to have the CONFIG_ prefix to
work with boards.cfg.

Signed-off-by: Shinya Kuribayashi <skuribay@pobox.com>
diff --git a/boards.cfg b/boards.cfg
index cb67d2a..d3edc9f 100644
--- a/boards.cfg
+++ b/boards.cfg
@@ -219,6 +219,10 @@
 dbau1550                     mips        mips        dbau1x00            -              -           dbau1x00:DBAU1550
 dbau1550_el                  mips        mips        dbau1x00            -              -           dbau1x00:DBAU1550
 gth2                         mips        mips
+incaip                       mips        mips
+incaip_100MHz                mips        mips        incaip              -              -           incaip:CPU_CLOCK_RATE=100000000
+incaip_133MHz                mips        mips        incaip              -              -           incaip:CPU_CLOCK_RATE=133000000
+incaip_150MHz                mips        mips        incaip              -              -           incaip:CPU_CLOCK_RATE=150000000
 pb1000                       mips        mips        pb1x00              -              -           pb1x00:PB1000
 purple                       mips        mips
 qemu_mips                    mips        mips        qemu-mips           -              -           qemu-mips