am33xx: fix the ddr_cmdtctrl structure

am33xx: fix the ddr_cmdtctrl structure

Fix the wrong mapping between the DDR I/O control registers on AM33XX
SoCs and the software representation in the SPL code.
The most recent public TRM defines the following DDR I/O control registers
offsets:
 * ddr_cmd0_ioctrl : offset 0x44E11404
 * ddr_cmd1_ioctrl : offset 0x44E11408
 * ddr_cmd2_ioctrl : offset 0x44E1140C
 * ddr_data0_ioctrl: offset 0x44E11440
 * ddr_data1_ioctrl: offset 0x44E11444

While the struct ddr_cmdtctrl has also some reserved bits in the beginning.
The struct is mapped to the address 0x44E11404. As a result "cm0ioctl" points
to the ddr_cmd1_ioctrl register, "cm1ioctl" to the ddr_cmd2_ioctrl and etc.
Registers ddr_cmd0_ioctrl and ddr_data0_ioctrl are never configured because
of this mapping mismatch.

Signed-off-by: Ilya Ledvich <ilya@compulab.co.il>
Reviewed-by: Peter Korsgaard <jacmet@sunsite.dk>