Fix warning reported by Coverity Scan.
Uninitialized scalar variable (UNINIT)
uninit_use: Using uninitialized value final. Field final.no_colour is
uninitialized.
Fixes: 3e4e849e6a96 ("panfrost: Disable tib read/write when colourmask = 0x0")
Signed-off-by: Vinson Lee <vlee@freedesktop.org>cc: @alyssa