platform/x86: thinkpad_acpi: Initialize local in_tablet_mode and type

linux-next reported in_tablet_mode and type may be used uninitialized
after:

b31800283868 ("platform/x86: thinkpad_acpi: Move tablet detection into separate function")

This turns out to be a false positive as the pr_info call cannot be
reached if tp_features.hotkey_tablet (global scope) is 0, and
in_tablet_mode and type are assigned in both places
tp_features.hotkey_tablet is assigned.

Regardless, to make it explicit and avoid further reports, initialize
in_tablet_mode to 0 and type to NULL.

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Lyude <lyude@redhat.com>

drivers/platform/x86/thinkpad_acpi.c

@@ -3143,8 +3143,8 @@ typedef tpacpi_keymap_entry_t tpacpi_keymap_t[TPACPI_HOTKEY_MAP_LEN];
 
 static int hotkey_init_tablet_mode(void)
 {
-	int in_tablet_mode, res;
-	char *type;
+	int in_tablet_mode = 0, res;
+	char *type = NULL;
 
 	if (acpi_evalf(hkey_handle, &res, "MHKG", "qd")) {
 		/* For X41t, X60t, X61t Tablets... */