Fix build break in linux driver.
Fix build break in linux driver.

Without this fix we get a "function declaration isn't a prototype" error
when building the driver.

Change-Id: I339337ff51bcab6d0b81f0e3067a5ce8f8ae0a44

project-oak/hafnium-verification,project-oak/hafnium-verification,project-oak/hafnium-verification,project-oak/hafnium-verification,project-oak/hafnium-verification,project-oak/hafnium-verification,project-oak/hafnium-verification