ACPI: thinkpad-acpi: make EC-based thermal readings non-experimental

Reading the 16 thermal sensors directly from the EC has been stable for
about one year, in all supported ThinkPad models.  Remove its
"experimental" label.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/misc/thinkpad_acpi.c

@@ -2709,7 +2709,7 @@ static int __init thermal_init(struct ibm_init_struct *iibm)
 
 	acpi_tmp7 = acpi_evalf(ec_handle, NULL, "TMP7", "qv");
 
-	if (thinkpad_id.ec_model && experimental) {
+	if (thinkpad_id.ec_model) {
 		/*
 		 * Direct EC access mode: sensors at registers
 		 * 0x78-0x7F, 0xC0-0xC7.  Registers return 0x00 for