ANDROID: mmc: MMC crypto API

Make mmc core able to use the blk-crypto framework for inline
encryption. This patch introduces a pointer to struct keyslot_manager
to struct mmc_host, and handles setting up the request_queue for
devices using that keyslot_manager appropriately. It also inits struct
mmc_request's inline encryption fields before it's passed to
mmc_host::ops->request.

Users of the core code in host/ (e.g. cqhci.c) should initialize the
keyslot_manager in struct mmc_host appropriately, if they want to
support inline encryption. They should also handle any inline
encryption related work necessary when mmc_host::ops->request is
called.

This patch is only compile tested, as I don't have a device to
actually test these patches. Enable CONFIG_MMC_CRYPTO to test

Bug: 153512828
Bug: 144046242
Change-Id: I6f98ffadfa6e39d7fdc3752b069210ad97babd8b
Co-developed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Satya Tangirala <satyat@google.com>