libubi.c: add klibc specific fixes for ioctl

libubi.c: add klibc specific fixes for ioctl

First issue is that ioctl() in klibc doesn't expect a constant as arg3.
Second issue is that arg3 in klibc ioctl() implementation is not optional.

Fixes:

| ubi-utils/libubi.c: In function 'do_attach':
| ubi-utils/libubi.c:698:8: warning: passing argument 3 of 'ioctl' discards
| 'const' qualifier from pointer target type
|   ret = ioctl(fd, UBI_IOCATT, r);
|         ^
| In file included from ubi-utils/libubi.c:32:0:
| .../lib/klibc/include/sys/ioctl.h:15:14: note: expected 'void *' but argument
| is of type 'const struct ubi_attach_req *'
|  __extern int ioctl(int, int, void *);
|               ^

| ubi-utils/libubi.c: In function 'ubi_vol_block_create':
| ubi-utils/libubi.c:1118:9: error: too few arguments to function 'ioctl'
|   return ioctl(fd, UBI_IOCVOLCRBLK);
|          ^
| In file included from ubi-utils/libubi.c:32:0:
| .../lib/klibc/include/sys/ioctl.h:15:14: note: declared here
|  __extern int ioctl(int, int, void *);
|               ^
| ubi-utils/libubi.c: In function 'ubi_vol_block_remove':
| ubi-utils/libubi.c:1123:9: error: too few arguments to function 'ioctl'
|   return ioctl(fd, UBI_IOCVOLRMBLK);
|          ^
| In file included from ubi-utils/libubi.c:32:0:
| .../usr/lib/klibc/include/sys/ioctl.h:15:14: note: declared here
|  __extern int ioctl(int, int, void *);
|               ^

Signed-off-by: Andrea Adami <andrea.adami@gmail.com>
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>