crypto: aesni - fix XTS mode on x86-32, add wrapper function for asmlinkage aesni_enc()

Calling convention for internal functions and 'asmlinkage' functions is
different on x86-32. Therefore do not directly cast aesni_enc as XTS tweak
function, but use wrapper function in between. Fixes crash with "XTS +
aesni_intel + x86-32" combination.

Cc: stable@vger.kernel.org
Reported-by: Krzysztof Kolasa <kkolasa@winsoft.pl>
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>