ACPI: thinkpad-acpi: fix hotkey_get_tablet_mode

I used the wrong return convention on hotkey_get_tablet_mode(), breaking a lot
of stuff. Bad Henrique!

Fix it to return the status in the parameter-by-reference, and IO status on
the function return value. Duh.

Signed-off-by: Henrique de Moraes Holschuh <[e-mail]>
Cc: Zdenek Kabelac <[e-mail]>
Cc: "Rafael J. Wysocki" <[e-mail]>
Cc: Lukas Hejtmanek <[e-mail]>
Cc: Len Brown <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/misc/thinkpad_acpi.c

···
 	if (!acpi_evalf(hkey_handle, &s, "MHKG", "d"))
 		return -EIO;
 
-	return ((s & TP_HOTKEY_TABLET_MASK) != 0);
+	*status = ((s & TP_HOTKEY_TABLET_MASK) != 0);
+	return 0;
 }
 
 /*