xilinx: common: change bootm_size to not go beyond ram_top

The available ram can be limited by ram_top as that depends on the
reserved memory nodes provided by the device-tree (via
board_get_usable_ram_top), so make sure to respect ram_top when setting
up bootm_size to avoid overlapping reserved memory regions (e.g. memory
used by OP-TEE).

The same logic is available in env_get_bootm_size when bootm_size is
not defined by the default environment.

Signed-off-by: Ricardo Salveti <ricardo@foundries.io>
Link: https://lore.kernel.org/r/20220120191730.2009270-1-ricardo@foundries.io
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/board/xilinx/common/board.c b/board/xilinx/common/board.c
index 78a5d0e..6fce231 100644
--- a/board/xilinx/common/board.c
+++ b/board/xilinx/common/board.c
@@ -377,7 +377,7 @@
 	u32 ret = 0;
 	int i, id, macid = 0;
 	struct xilinx_board_description *desc;
-	phys_size_t bootm_size = gd->ram_size;
+	phys_size_t bootm_size = gd->ram_top - gd->ram_base;
 
 	if (!CONFIG_IS_ENABLED(MICROBLAZE)) {
 		ulong scriptaddr;