Accton AS5600_52X: Add to support ONIE

Due to the ONIE partition size on NOR flash is not large enough, we
decide to remove the support of EXT3 tools and MTD utilities from
now on.

The NOS installer shall use EXT2 tools instead of EXT3 ones.

Signed-off-by: Curt Brune <curt@cumulusnetworks.com>
Accton AS5610_52X: Add to support ONIE

Due to the ONIE partition size on NOR flash is not large enough, we
decide to remove the support of EXT3 tools and MTD utilities from
now on.

The NOS installer shall use EXT2 tools instead of EXT3 ones.

Signed-off-by: Curt Brune <curt@cumulusnetworks.com>