units: Add BYTES_PER_*BIT

There is going to be a new user of the BYTES_PER_[K/M/G]BIT definition
besides possibly existing ones. Add them to the header.
Signed-off-by: Damian Muszynski <damian.muszynski@intel.com>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Reviewed-by: Tero Kristo <tero.kristo@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/linux/units.h

@@ -31,6 +31,10 @@
 #define MICROWATT_PER_MILLIWATT	1000UL
 #define MICROWATT_PER_WATT	1000000UL
 
+#define BYTES_PER_KBIT		(KILO / BITS_PER_BYTE)
+#define BYTES_PER_MBIT		(MEGA / BITS_PER_BYTE)
+#define BYTES_PER_GBIT		(GIGA / BITS_PER_BYTE)
+
 #define ABSOLUTE_ZERO_MILLICELSIUS -273150
 
 static inline long milli_kelvin_to_millicelsius(long t)