units: Add Watt units

stable inclusion
from stable-v5.10.166
commit 974aaf11804f658aad8b03e3950e41c80efd04a8
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7TH9O

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=974aaf11804f658aad8b03e3950e41c80efd04a8

--------------------------------

[ Upstream commit 2ee5f8f0 ]

As there are the temperature units, let's add the Watt macros definition.
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: NLukasz Luba <lukasz.luba@arm.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Stable-dep-of: c8c37bc5 ("i2c: designware: use casting of u64 in clock multiplication to avoid overflow")
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: Nsanglipeng <sanglipeng1@jd.com>

include/linux/units.h

@@ -4,6 +4,10 @@
 
 #include <linux/kernel.h>
 
+#define MILLIWATT_PER_WATT	1000L
+#define MICROWATT_PER_MILLIWATT	1000L
+#define MICROWATT_PER_WATT	1000000L
+
 #define ABSOLUTE_ZERO_MILLICELSIUS -273150
 
 static inline long milli_kelvin_to_millicelsius(long t)