omap3_overo: Reduce SPL size

Borrowing from omap3_logic, switch to SPL_SYS_MALLOC_SIMPLE and moving
the stack to DDR as soon as we're able.

Signed-off-by: Tom Rini <trini@konsulko.com>

configs/omap3_overo_defconfig

@@ -4,6 +4,10 @@ CONFIG_TARGET_OMAP3_OVERO=y
 CONFIG_SYS_CONSOLE_INFO_QUIET=y
 CONFIG_VERSION_VARIABLE=y
 CONFIG_SPL=y
+CONFIG_SPL_SYS_MALLOC_SIMPLE=y
+CONFIG_SPL_STACK_R_ADDR=0x82000000
+CONFIG_SPL_STACK_R=y
+CONFIG_SYS_MALLOC_F_LEN=0x2000
 CONFIG_SPL_MTD_SUPPORT=y
 CONFIG_SPL_OS_BOOT=y
 CONFIG_HUSH_PARSER=y