targets/orangecrab: use new ECP5DDRPHY's cmd_delay to add extra delay on DDR3's Clock/Commands.
targets/orangecrab: use new ECP5DDRPHY's cmd_delay to add extra delay on DDR3's Clock/Commands.

This fixes https://github.com/enjoy-digital/litedram/issues/130 and has been tested
at 48/64/96MHz on MT41K64M16 and MT41K512M16 variants.

Also remove un-needed cd_sys2x_eb.

litex-hub/litex-boards