gpio/basic_mmio: add missing include of spinlock_types.h

include/linux/basic_mmio_gpio.h uses a spinlock_t without including any
of the spinlock headers resulting in this compiler warning.

include/linux/basic_mmio_gpio.h:51:2: error: expected specifier-qualifier-list before 'spinlock_t'

Explicitly include linux/spinlock_types.h to fix it.
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

include/linux/basic_mmio_gpio.h

@@ -16,6 +16,7 @@
 #include <linux/gpio.h>
 #include <linux/types.h>
 #include <linux/compiler.h>
+#include <linux/spinlock_types.h>
 
 struct bgpio_pdata {
 	int base;