platform/x86: hp-wmi: Fix error value for hp_wmi_tablet_state

BugLink: http://bugs.launchpad.net/bugs/1732698

commit c7dfc2fa upstream.

hp_wmi_tablet_state() fails to return the correct error code when
hp_wmi_perform_query() returns the HP WMI query specific error code
that is a positive value.
Signed-off-by: Carlo Caione <carlo@endlessm.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
Cc: Philip Müller <philm@manjaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

drivers/platform/x86/hp-wmi.c

@@ -291,7 +291,7 @@ static int hp_wmi_tablet_state(void)
 	int ret = hp_wmi_perform_query(HPWMI_HARDWARE_QUERY, 0, &state,
 				       sizeof(state), sizeof(state));
 	if (ret)
-		return ret;
+		return -EINVAL;
 
 	return (state & 0x4) ? 1 : 0;
 }