testing/drivers/fftest/fftest.c: fix compilation error

fix compilation error:

CC:  vfs/fs_rmdir.c fftest.c: In function ‘fftest_main’:
fftest.c:104:7: error: implicit declaration of function ‘ioctl’ [-Wimplicit-function-declaration]
  104 |   if (ioctl(fd, EVIOCGBIT, fffeatures) < 0)

Signed-off-by: raiden00pl <raiden00@railab.me>

Author: raiden00pl

testing/drivers/fftest/fftest.c

@@ -30,6 +30,8 @@
 #include <string.h>
 #include <unistd.h>
 
+#include <sys/ioctl.h>
+
 #include <nuttx/bits.h>
 #include <nuttx/fs/ioctl.h>
 #include <nuttx/input/ff.h>