drivers/firmware/efi/efivars.c: use in_compat_syscall() to check for compat callers

This should make no difference on any architecture, as x86's historical
is_compat_task behavior really did check whether the calling syscall was
a compat syscall.  x86's is_compat_task is going away, though.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/firmware/efi/efivars.c

@@ -231,7 +231,7 @@ sanity_check(struct efi_variable *var, efi_char16_t *name, efi_guid_t vendor,
 
 static inline bool is_compat(void)
 {
-	if (IS_ENABLED(CONFIG_COMPAT) && is_compat_task())
+	if (IS_ENABLED(CONFIG_COMPAT) && in_compat_syscall())
 		return true;
 
 	return false;