i2c: Remove deprecated individual i2c commands

The following individual I2C commands have been removed: imd, imm, inm,
imw, icrc32, iprobe, iloop, isdram.

The functionality of the individual commands is still available via
the 'i2c' command.

This change only has an impact on those boards which did not have
CONFIG_I2C_CMD_TREE defined.

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>