Correct references to swiotlb_tbl_map_single() and
swiotlb_tbl_unmap_single() in the documentation for swiotlb.

Fix two small typos that went unnoticed in commit c93f261dfc39
("Documentation/core-api: add swiotlb documentation"):
swiotlb_tlb_map_single --> swiotlb_tbl_map_single
swiotbl_tlb_unmap_single --> swiotlb_tbl_unmap_single

Signed-off-by: Eder Zulian <ezulian@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20241014224026.1838525-1-ezulian@redhat.com

Commit c93f261dfc39 ("Documentation/core-api: add swiotlb documentation")
accidentally refers to CONFIG_DYNAMIC_SWIOTLB in one place, while the
config is actually called CONFIG_SWIOTLB_DYNAMIC.

Correct the reference to the intended config option.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Reviewed-by: Petr Tesarik <petr@tesarici.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>

There's currently no documentation for the swiotlb. Add documentation
describing usage scenarios, the key APIs, and implementation details.
Group the new documentation with other DMA-related documentation.

Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Petr Tesarik <petr@tesarici.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>