board: ti: am62x: Use fdt functions for ram and bank init

Use the appropriate fdtdec_setup_mem_size_base() call in
dram_init() and fdtdec_setup_bank_size() in dram_bank_init()
to pull these values from DT, where they are already available,
instead of hardcoding them.

Signed-off-by: Georgi Vlaev <g-vlaev@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/board/ti/am62x/evm.c b/board/ti/am62x/evm.c
index 4dd5e64..fb5106d 100644
--- a/board/ti/am62x/evm.c
+++ b/board/ti/am62x/evm.c
@@ -23,17 +23,10 @@
 
 int dram_init(void)
 {
-	gd->ram_size = 0x80000000;
-
-	return 0;
+	return fdtdec_setup_mem_size_base();
 }
 
 int dram_init_banksize(void)
 {
-	/* Bank 0 declares the memory available in the DDR low region */
-	gd->bd->bi_dram[0].start = CONFIG_SYS_SDRAM_BASE;
-	gd->bd->bi_dram[0].size = 0x80000000;
-	gd->ram_size = 0x80000000;
-
-	return 0;
+	return fdtdec_setup_memory_banksize();
 }