isl: Fix some tautological-compare warnings

Fixes:
isl.c:62:22: warning: self-comparison always evaluates to true [-Wtautological-compare]
    assert(ISL_DEV_GEN(dev) == dev->info->gen);
                      ^~
isl.c:63:33: warning: self-comparison always evaluates to true [-Wtautological-compare]
    assert(ISL_DEV_USE_SEPARATE_STENCIL(dev) == dev->use_separate_stencil);

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
2 files changed