drm/i915: Add engine name to workaround debug print

There is a debug message in the workaround initialisation path that
reports how many entries were added of each type. However, whitelist
workarounds exist for multiple engines but the type name is just
'whitelist'. Tvrtko suggested adding the engine name to make the
message more useful.

v2: Updated the similar message in the workaround reset selftest.

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
CC: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190712070745.35239-4-John.C.Harrison@Intel.com