Revert "spi: axi-spi-engine: simplify driver data allocation"

This reverts commit be632e90 which is
commit 9e4ce522 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I53033e5988e2e24fee2847555b1c148ef6aea4c1
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>