localboot: Include header files for function prototypes

localboot: Include header files for function prototypes

... to avoid the following warnings,

localboot.c: In function ‘local_boot’:
localboot.c:38:2: warning: implicit declaration of function ‘vgaclearmode’
localboot.c:40:2: warning: implicit declaration of function ‘writestr’
localboot.c:41:2: warning: implicit declaration of function ‘crlf’
localboot.c:42:2: warning: implicit declaration of function ‘cleanup_hardware’
localboot.c:76:2: warning: implicit declaration of function ‘memcpy’

Signed-off-by: Matt Fleming <matt.fleming@intel.com>