efi/x86: Mark setup_graphics static

This function is only called from efi_main in the same source file.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200130222004.1932152-1-nivedita@alum.mit.eduSigned-off-by: Ard Biesheuvel <ardb@kernel.org>

arch/x86/boot/compressed/eboot.c

@@ -315,7 +315,7 @@ setup_uga(struct screen_info *si, efi_guid_t *uga_proto, unsigned long size)
 	return status;
 }
 
-void setup_graphics(struct boot_params *boot_params)
+static void setup_graphics(struct boot_params *boot_params)
 {
 	efi_guid_t graphics_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
 	struct screen_info *si;