hw/arm_boot.c: Make ram_size a uint64_t

Make the RAM size in arm_boot_info a uint64_t so it can express
the larger RAM sizes that may be seen in LPAE systems.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter A. G. Crosthwaite <peter.crosthwaite@petalogix.com>

hw/arm-misc.h

@@ -25,7 +25,7 @@ qemu_irq *armv7m_init(MemoryRegion *address_space_mem,
 
 /* arm_boot.c */
 struct arm_boot_info {
-    int ram_size;
+    uint64_t ram_size;
     const char *kernel_filename;
     const char *kernel_cmdline;
     const char *initrd_filename;