usb: isp1760: hcd: refactor mempool config and setup

In preparation to support other family member IP, which may have
different memory layout. Drop macros and setup a configuration
struct.

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Link: https://lore.kernel.org/r/20210513084717.2487366-6-rui.silva@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>