Use the correct fuse_init_out structure size.

Kernel 2.6.16 is the first stable kernel with struct fuse_init_out
defined (fuse version 7.6). The structure is the same from 7.6 through
7.22. Beginning with 7.23, the structure increased in size and added
new parameters.

If the kernel only works on minor revs older than or equal to 22,
then use the older structure size since this code only uses the 7.22
version of the structure.

Change-Id: If2507a02ad674fcf02869a325221339ae1ace64d