common: return type board_get_usable_ram_top

board_get_usable_ram_top() returns a physical address that is stored in
gd->ram_top. The return type of the function should be phys_addr_t like the
current type of gd->ram_top.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/board/ti/j721s2/evm.c b/board/ti/j721s2/evm.c
index 8eaca9d..7795300 100644
--- a/board/ti/j721s2/evm.c
+++ b/board/ti/j721s2/evm.c
@@ -43,7 +43,7 @@
 	return 0;
 }
 
-phys_size_t board_get_usable_ram_top(phys_size_t total_size)
+phys_addr_t board_get_usable_ram_top(phys_size_t total_size)
 {
 #ifdef CONFIG_PHYS_64BIT
 	/* Limit RAM used by U-Boot to the DDR low region */