mmc: renesas_sdhi: Fix typo's

mmc: renesas_sdhi: Fix typo's

Fix typo's,
* difference -> different
* alignment -> aligned

While at it updated the comment to make it clear that Renesas SDHI DMAC
needs buffers to be 128-byte aligned.

Reported-by: Pavel Machek <pavel@denx.de>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20220624181438.4355-3-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>