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/arch/arm/mach-stm32mp/dram_init.c b/arch/arm/mach-stm32mp/dram_init.c
index 80ba5c2..7f37b0d 100644
--- a/arch/arm/mach-stm32mp/dram_init.c
+++ b/arch/arm/mach-stm32mp/dram_init.c
@@ -40,7 +40,7 @@
 	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)
 {
 	phys_size_t size;
 	phys_addr_t reg;