Now works as expected with the lda parameter.

* LDA specifies the real size of the leading dimension of the array, so
you can have more memory reserved than used.
* If A is not transposed and k == lda, we only make one call per
device to write the buffer (because all the elements are adjacent),
expecting to save a little bit of time.
* lda, ldb and ldc are removed from the call to the OpenCL kernel.

Many thanks again to @josecriane for helping me a lot on this stage.