vgacon: fix mips/sibyte build regression

The conversion to vgacon_register_screen() was missing an #include statement
for the swarm board:

arch/mips/sibyte/swarm/setup.c:146:9: error: implicit declaration of function 'vgacon_register_screen' [-Werror=implicit-function-declaration]

Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Fixes: 555624c0d10b vgacon: clean up global screen_info instances
Signed-off-by: Arnd Bergmann <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

arch/mips/sibyte/swarm/setup.c

···
 #include <linux/memblock.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/console.h>
 #include <linux/screen_info.h>
 #include <linux/initrd.h>