gpio: xtensa: fix build when XCHAL_HAVE_CP is 0

In xtensa coprocessors may exist without coprocessor context, i.e. they cannot
be disabled/enabled. In this case the RSR_CPENABLE/WSR_CPENABLE are undefined,
thus breaking the build. Fix the build by adding dummy versions of
enable_cp/disable_cp in this case.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-xtensa.c

@@ -40,6 +40,8 @@
 #error GPIO32 option is not enabled for your xtensa core variant
 #endif
 
+#if XCHAL_HAVE_CP
+
 static inline unsigned long enable_cp(unsigned long *cpenable)
 {
 	unsigned long flags;
@@ -57,6 +59,20 @@ static inline void disable_cp(unsigned long flags, unsigned long cpenable)
 	local_irq_restore(flags);
 }
 
+#else
+
+static inline unsigned long enable_cp(unsigned long *cpenable)
+{
+	*cpenable = 0; /* avoid uninitialized value warning */
+	return 0;
+}
+
+static inline void disable_cp(unsigned long flags, unsigned long cpenable)
+{
+}
+
+#endif /* XCHAL_HAVE_CP */
+
 static int xtensa_impwire_get_direction(struct gpio_chip *gc, unsigned offset)
 {
 	return 1; /* input only */