Up until now algorithms have been happy to get a context pointer since
they know everything that's in the tfm already (e.g., alignment, block
size).

However, once we have parameterised algorithms, such information will
be specific to each tfm.  So the algorithm API needs to be changed to
pass the tfm structure instead of the context pointer.

This patch is basically a text substitution.  The only tricky bit is
the assembly routines that need to get the context pointer offset
through asm-offsets.h.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>