ARM: pxa: fix pxa_ssp_* declarations

The functions declared in include/linux/pxa2xx_ssp.h are
defined in plat-pxa/ssp.c, which can also be built for
PLAT_MMP, but may be disabled there. This can lead to
both unresolved symbols at link time and to duplicate
symbols at compile time for random configurations.

Changing the #ifdef in the header file to match the
Kconfig symbol that decides if the file is built solves
both problems.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Daniel Mack <zonque@gmail.com>

include/linux/pxa2xx_ssp.h

@@ -219,7 +219,7 @@ static inline u32 pxa_ssp_read_reg(struct ssp_device *dev, u32 reg)
 	return __raw_readl(dev->mmio_base + reg);
 }
 
-#ifdef CONFIG_ARCH_PXA
+#if IS_ENABLED(CONFIG_PXA_SSP)
 struct ssp_device *pxa_ssp_request(int port, const char *label);
 void pxa_ssp_free(struct ssp_device *);
 struct ssp_device *pxa_ssp_request_of(const struct device_node *of_node,