mmc: sdio: fix alignment issue in struct sdio_func

[ Upstream commit 5ef1ecf0 ]

Certain 64-bit systems (e.g. Amlogic Meson GX) require buffers to be
used for DMA to be 8-byte-aligned. struct sdio_func has an embedded
small DMA buffer not meeting this requirement.
When testing switching to descriptor chain mode in meson-gx driver
SDIO is broken therefore. Fix this by allocating the small DMA buffer
separately as kmalloc ensures that the returned memory area is
properly aligned for every basic data type.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Tested-by: Helmut Klein <hgkr.klein@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>