MLK-17153-2 imx8mq_arm2: Resolve malloc memory problem for SPL NAND boot

MLK-17153-2 imx8mq_arm2: Resolve malloc memory problem for SPL NAND boot

When using SPL NAND boot, the required malloc memory is larger than SD/eMMC boot.
Since we have used out OCRAM (for ATF) and OCRAM_S, there is no enough memory could be
allocated.

The solution is moving the malloc memory pool to DDR. The malloc pool is initialized in
board_init_r, so we moved the VDD_DRAM adjustment and DDR init to board_init_f. Then the DDR
can setup before memory pool initialization. Because the i2c and PMIC driver needs to malloc
data, this change has to enable malloc_f pool by setting CONFIG_MALLOC_F_ADDR to previous
malloc address on OCRAM_S.

Signed-off-by: Ye Li <ye.li@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>