dt-bindings: property-units: Sanitize unit naming

Make the naming of units consistent with common practices:
  - Do not capitalize the first character of units ("Celsius" is
    special, as it is not the unit name, but a reference to its
    proposer),
  - Do not use plural for units,
  - Do not abbreviate "ampere",
  - Concatenate prefixes and units (no spaces or hyphens),
  - Separate units by spaces not hyphens,
  - "milli" applies to "degree", not to "Celsius".

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/property-units.txt

@@ -12,32 +12,32 @@ unit prefixes.
 Time/Frequency
 ----------------------------------------
 -mhz		: megahertz
--hz		: Hertz (preferred)
--sec		: seconds
--ms		: milliseconds
--us		: microseconds
--ns		: nanoseconds
+-hz		: hertz (preferred)
+-sec		: second
+-ms		: millisecond
+-us		: microsecond
+-ns		: nanosecond
 
 Distance
 ----------------------------------------
--mm		: millimeters
+-mm		: millimeter
 
 Electricity
 ----------------------------------------
--microamp	: micro amps
--microamp-hours : micro amp-hours
--ohms		: Ohms
--micro-ohms	: micro Ohms
--microwatt-hours: micro Watt-hours
--microvolt	: micro volts
--picofarads	: picofarads
--femtofarads	: femtofarads
+-microamp	: microampere
+-microamp-hours : microampere hour
+-ohms		: ohm
+-micro-ohms	: microohm
+-microwatt-hours: microwatt hour
+-microvolt	: microvolt
+-picofarads	: picofarad
+-femtofarads	: femtofarad
 
 Temperature
 ----------------------------------------
--celsius	: Degrees Celsius
--millicelsius	: Degreee milli-Celsius
+-celsius	: degree Celsius
+-millicelsius	: millidegree Celsius
 
 Pressure
 ----------------------------------------
--kpascal	: kiloPascal
+-kpascal	: kilopascal