x86: shrink video_{flags,mode} to {8,16} bits

We really don't need them to be any wider.

Also remove the C level declaration (and hence also the GLOBAL) of
video_mode altogether; it's used in assembly code only.

Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2: New.

--- a/xen/arch/x86/boot/wakeup.S
+++ b/xen/arch/x86/boot/wakeup.S
@@ -82,10 +82,9 @@ bogus_real_magic:
 
         .align 4
 real_magic:     .long 0x12345678
-GLOBAL(video_mode)
-        .long 0
+video_mode:     .word 0
 GLOBAL(video_flags)
-        .long 0
+        .byte 0
 
         .code32
 
--- a/xen/include/asm-x86/config.h
+++ b/xen/include/asm-x86/config.h
@@ -99,7 +99,9 @@ extern char trampoline_realmode_entry[];
 extern unsigned int trampoline_xen_phys_start;
 extern unsigned char trampoline_cpu_started;
 extern char wakeup_start[];
-extern unsigned int video_mode, video_flags;
+
+extern unsigned char video_flags;
+
 extern unsigned short boot_edid_caps;
 extern unsigned char boot_edid_info[128];
 #endif