drm/msm/dsi/phy: Replace hardcoded char-array length with sizeof()

Now that the last DSI PHY PLL driver (dsi_phy_28nm_8960) has been
converted to use a simple stack-local char-array instead of a
devm_kzalloc heap allocation we can safely call sizeof() on every string
variable (that's now a sized array instead of a pointer) passed into
snprintf instead of hardcoding the size.

Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/491920/
Link: https://lore.kernel.org/r/20220629225331.357308-7-marijn.suijten@somainline.org


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>