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

Documentation/driver-api/dma-buf.rst

@@ -77,7 +77,7 @@ consider though:
   the usual size discover pattern size = SEEK_END(0); SEEK_SET(0). Every other
   llseek operation will report -EINVAL.
 
-  If llseek on dma-buf FDs isn't support the kernel will report -ESPIPE for all
+  If llseek on dma-buf FDs isn't supported the kernel will report -ESPIPE for all
   cases. Userspace can use this to detect support for discovering the dma-buf
   size using llseek.