ARM: rmobile: Set maximum kernel size to 64 MiB on Gen3

The Gen3 kernel images are often above 8 MiB, increase the
maximum kernel size to 64 MiB to future-proof it, just like
many other ARM64 boards do.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>

include/configs/rcar-gen3-common.h

@@ -51,6 +51,7 @@
 #define CONFIG_SYS_MONITOR_LEN		(256 * 1024)
 #define CONFIG_SYS_MALLOC_LEN		(1 * 1024 * 1024)
 #define CONFIG_SYS_BOOTMAPSZ		(8 * 1024 * 1024)
+#define CONFIG_SYS_BOOTM_LEN		(64 << 20)
 
 /* ENV setting */
 #define CONFIG_ENV_OVERWRITE