doc: dma-buf: fix grammar typo

Use 'supported' instead of 'support'. 'support' makes no sense in this
context.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Link: https://patchwork.freedesktop.org/patch/msgid/505484b83fedebce3c65b10b076b34df075074b6.1713329988.git.baruch@tkos.co.il


Signed-off-by: Christian König <christian.koenig@amd.com>