drm/i915/tgl: Don't treat unslice registers as masked

The UNSLICE_UNIT_LEVEL_CLKGATE and UNSLICE_UNIT_LEVEL_CLKGATE2 registers
that we update in a few engine workarounds are not masked registers
(i.e., we don't have to write a mask bit in the top 16 bits when
updating one of the lower 16 bits).  As such, these workarounds should
be applied via wa_write_or() rather than wa_masked_en()

v2:
 - Rebase

Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Reported-by: kernelci.org bot <bot@kernelci.org>
References: https://github.com/ClangBuiltLinux/linux/issues/918


Fixes: 50148a25 ("drm/i915/tgl: Move and restrict Wa_1408615072")
Fixes: 3551ff92 ("drm/i915/gen11: Moving WAs to rcs_engine_wa_init()")
Cc: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200306171139.1414649-1-matthew.d.roper@intel.com