Nokia RX-51: Convert to CONFIG_DM_SERIAL

For CONFIG_DM_SERIAL it is required to increase CONFIG_SYS_MALLOC_F_LEN as
default value is not enough for memory hungry CONFIG_DM_SERIAL code.

Signed-off-by: Pali Rohár <pali@kernel.org>
Tested-by: Merlijn Wajer <merlijn@wizzup.org>
3 files changed