common: spl: Add interactive DDR debugger support for SPL image

common: spl: Add interactive DDR debugger support for SPL image

To support interactive DDR debugger, cli_simple.o, cli.o, cli_readline.o,
command.o, s_record.o, xyzModem.o and cmd_disk.o are all needed for
drivers/ddr/fsl/interactive.c.

In current common/Makefile, the above .o files are only produced when
CONFIG_SPL_BUILD is disabled.

For LS102xA, interactive DDR debugger is needed in SD/NAND boot too, and
I enabled CONFIG_FSL_DDR_INTERACTIVE. But according to the current
common/Makfile, all the above .o files are not produced in SPL part
because CONFIG_SPL_BUILD is enabled in SPL part, the following error
will be shown,

drivers/ddr/fsl/built-in.o: In function `fsl_ddr_interactive':
/home/wangh/layerscape/u-boot/drivers/ddr/fsl/interactive.c:1871:
undefined reference to `cli_readline_into_buffer'
/home/wangh/layerscape/u-boot/drivers/ddr/fsl/interactive.c:1873:
undefined reference to `cli_simple_parse_line'
make[1]: *** [spl/u-boot-spl] Error 1
make: *** [spl/u-boot-spl] Error 2

So this patch fixed this issue and the above .o files will be produced
no matter CONFIG_SPL_BUILD is enabled or disabled.

Signed-off-by: Alison Wang <alison.wang@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>