[PATCH v6 1/3] phy: mediatek: fix build warning caused by clang

[Chunfeng Yun]

Remove the temporary @mask_, this may cause build warning when use clang
compiler for powerpc, but can't reproduce it when compile for arm64.
the build warning is -Wtautological-constant-out-of-range-compare, and
caused by
"BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask)"

After removing @mask_, there is a "CHECK:MACRO_ARG_REUSE" when run
checkpatch.pl, due to @mask is constant, no reuse problem will happen.

Fixes: 84513eccd678 ("phy: mediatek: fix build warning of FIELD_PREP()")
Reported-by: kernel test robot <lkp at intel.com>
Signed-off-by: Chunfeng Yun <chunfeng.yun at mediatek.com>
---
v6: modify the title
v5: no changes
v4 new patch, I'm not sure it can fix build warning, due to I don't cross compile
    it for powerpc using clang in office.
---
 drivers/phy/mediatek/phy-mtk-io.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/mediatek/phy-mtk-io.h b/drivers/phy/mediatek/phy-mtk-io.h
index d20ad5e5be81..58f06db822cb 100644
--- a/drivers/phy/mediatek/phy-mtk-io.h
+++ b/drivers/phy/mediatek/phy-mtk-io.h
@@ -39,8 +39,8 @@ static inline void mtk_phy_update_bits(void __iomem *reg, u32 mask, u32 val)
 /* field @mask shall be constant and continuous */
 #define mtk_phy_update_field(reg, mask, val) \
 ({ \
-	typeof(mask) mask_ = (mask);	\
-	mtk_phy_update_bits(reg, mask_, FIELD_PREP(mask_, val)); \
+	BUILD_BUG_ON_MSG(!__builtin_constant_p(mask), "mask is not constant"); \
+	mtk_phy_update_bits(reg, mask, FIELD_PREP(mask, val)); \
 })
 
 #endif
-- 
2.18.0