ARM: da850evm: Enable SPL_SYS_MALLOC_SIMPLE

ARM: da850evm: Enable SPL_SYS_MALLOC_SIMPLE

The SPL space is limited.  In order to try to enable DM in SPL,
we need more space. When combined wtih TINY_PRINTF, this reduces
the size of SPL by 6.5k

Original:

   text	   data	    bss	    dec	    hex	filename
  20760	   1216	     80	  22056	   5628	spl/u-boot-spl

Tiny Printf
   text	   data	    bss	    dec	    hex	filename
  17947	   1216	     80	  19243	   4b2b	spl/u-boot-spl

Malloc Simple + Tiny Printf
   text	   data	    bss	    dec	    hex	filename
  15187	    176	     28	  15391	   3c1f	spl/u-boot-spl

Signed-off-by: Adam Ford <aford173@gmail.com>