docs: Minor spelling fix in spi documentation

Signed-off-by: Stéphane Blondon <stephane.blondon@gmail.com>
Link: https://lore.kernel.org/r/CAOy+up7EdTf4ouh5onVy_ZzXFWGBEP+P6CPqY-=E+1UFwCeq8w@mail.gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
1 file changed