qemu-arm: set CONFIG_SYS_BOOTM_LEN to SZ_64M

FIT image contents can be larger than default bootm limit 8M
with initrd. Raise limit to 64MB which is commonly used
elsewhere.

Signed-off-by: Dhananjay Phadke <dphadke@linux.microsoft.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

include/configs/qemu-arm.h

@@ -17,6 +17,8 @@
 #define CONFIG_SYS_LOAD_ADDR		(CONFIG_SYS_SDRAM_BASE + SZ_2M)
 #define CONFIG_SYS_MALLOC_LEN		SZ_16M
 
+#define CONFIG_SYS_BOOTM_LEN		SZ_64M
+
 /* For timer, QEMU emulates an ARMv7/ARMv8 architected timer */
 #define CONFIG_SYS_HZ                       1000