sparc32: use FW_CFG_CMDLINE_SIZE

Add support for getting kernel command line size with
FW_CFG_CMDLINE_SIZE.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

hw/sun4m.c

diff --git a/hw/sun4m.c b/hw/sun4m.c
index e7a4cf6..a1373d4 100644
--- a/hw/sun4m.c
+++ b/hw/sun4m.c
@@ -978,8 +978,11 @@
         fw_cfg_add_bytes(fw_cfg, FW_CFG_CMDLINE_DATA,
                          (uint8_t*)strdup(kernel_cmdline),
                          strlen(kernel_cmdline) + 1);
+        fw_cfg_add_i32(fw_cfg, FW_CFG_CMDLINE_SIZE,
+                       strlen(kernel_cmdline) + 1);
     } else {
         fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_CMDLINE, 0);
+        fw_cfg_add_i32(fw_cfg, FW_CFG_CMDLINE_SIZE, 0);
     }
     fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_ADDR, INITRD_LOAD_ADDR);
     fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_SIZE, 0); // not used