efi/libstub: Include dependencies of efistub.h

Add #include directives for include files that efistub.h depends on,
instead of relying on them having been included by the C source files
prior to efistub.h.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200518190716.751506-2-nivedita@alum.mit.eduSigned-off-by: Ard Biesheuvel <ardb@kernel.org>

drivers/firmware/efi/libstub/efistub.h

@@ -3,6 +3,11 @@
 #ifndef _DRIVERS_FIRMWARE_EFI_EFISTUB_H
 #define _DRIVERS_FIRMWARE_EFI_EFISTUB_H
 
+#include <linux/efi.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <asm/efi.h>
+
 /* error code which can't be mistaken for valid address */
 #define EFI_ERROR	(~0UL)