doc: release-notes/3.3: add release notes for SD host controller

Add release notes for SD host controller drivers for 3.3.
The following changes are highlighted:
- Added support for HS400 mode and HS200 mode in i.MX RT USDHC driver
- Added support for DMA operation on systems without NOCACHE memory
  to i.MX RT USDHC driver

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>