arm, davinci: perform check for initializing global data and serial init

arm, davinci: perform check for initializing global data and serial init

initialize baudrate, flags, data and serial initialization,
only when CONFIG_SPL_LIBCOMMON_SUPPORT is defined.

Tested-by: Christian Riesch <christian.riesch@omicron.at>
Signed-off-by: Lad, Prabhakar <prabhakar.lad@ti.com>
Signed-off-by: Rajashekhara, Sudhakar <sudhakar.raj@ti.com>
Signed-off-by: Hadli, Manjunath <manjunath.hadli@ti.com>
Acked-by: Christian Riesch <christian.riesch@omicron.at>