mraa: Correct spelling of capabilities

Type was correctly spelt, but the member in the platform strut was not.
My mistake from 2014.

Signed-off-by: Thomas Ingleby <thomas.ingleby@intel.com>

src/aio/aio.c

@@ -113,7 +113,7 @@ mraa_aio_init(unsigned int aio)
         syslog(LOG_ERR, "aio: requested channel out of range");
         return NULL;
     }
-    if (board->pins[pin].capabilites.aio != 1) {
+    if (board->pins[pin].capabilities.aio != 1) {
         syslog(LOG_ERR, "aio: pin %i not capable of aio", pin);
         return NULL;
     }