losetup: use LOOP_CONFIGURE in a more robust way

losetup: use LOOP_CONFIGURE in a more robust way

32-bit userspace returns ENOTTY:
 ioctl(4, LOOP_CONFIGURE, {fd=3, block_size=0, info={lo_offset=0, lo_number=0, lo_flags=LO_FLAGS_AUTOCLEAR, lo_file_name="/usr/install/iso/systemrescue-8.04-amd64.iso", ...}}) = -1 ENOTTY (Inappropriate ioctl for device)

64-bit userspace returns EINVAL:
 ioctl(4, LOOP_CONFIGURE, {fd=3, block_size=0, info={lo_offset=0, lo_number=0, lo_flags=LO_FLAGS_AUTOCLEAR, lo_file_name="/usr/src/PACKAGES/systemrescue-8.04-amd64.iso", ...}}) = -1 EINVAL (Invalid argument)

The correct return value for an unknown ioctl is ENOTTY, but we need
to support already released kernels, so let's support both errnos.

Reported-by: Krzysztof Olędzki <ole@ans.pl>
Signed-off-by: Karel Zak <kzak@redhat.com>