ARM: pxa: mark spitz_card_pwr_ctrl as __maybe_unused

This function is only used when CONFIG_PCMCIA is enabled, otherwise
we get a harmless warning:

arch/arm/mach-pxa/spitz.c:204:13: warning: 'spitz_card_pwr_ctrl' defined but not used [-Wunused-function]

Marking it as __maybe_unused keeps the logic simple and avoids the
warning on randconfig builds.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>

arch/arm/mach-pxa/spitz.c

@@ -201,7 +201,7 @@ static void __init spitz_scoop_init(void)
 }
 
 /* Power control is shared with between one of the CF slots and SD */
-static void spitz_card_pwr_ctrl(uint8_t enable, uint8_t new_cpr)
+static void __maybe_unused spitz_card_pwr_ctrl(uint8_t enable, uint8_t new_cpr)
 {
 	unsigned short cpr;
 	unsigned long flags;