cifs: Get rid of unneeded conditional in the smb2_get_aead_req()

In the smb2_get_aead_req() the skip variable is used only for
the very first iteration of the two nested loops, which means
it's basically in invariant to those loops. Hence, instead of
using conditional on each iteration, unconditionally assign
the 'skip' variable before the loops and at the end of the
inner loop.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>