lib: fdtdec: Rename routine fdtdec_setup_memory_size()

lib: fdtdec: Rename routine fdtdec_setup_memory_size()

This patch renames the routine fdtdec_setup_memory_size()
to fdtdec_setup_mem_size_base() as it now fills the
mem base as well along with size.

Signed-off-by: Siva Durga Prasad Paladugu <siva.durga.paladugu@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Tom Rini <trini@konsulko.com>