MIPS: fix allmodconfig build with latest mkimage

With the latest mkimage from U-Boot 2021.04+ the allmodconfig build
fails. 822564cd ("MIPS: generic: Update node names to avoid unit
addresses") was applied for similar build failure, but it was not
applied to 'arch/mips/generic/board-ocelot_pcb123.its.S' as that was
removed from upstream when the patch was applied.

Fixes: 822564cd ("MIPS: generic: Update node names to avoid unit addresses")
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>