gluon-status-page: avoid complex math

This code is usually running on an embedded CPU without FPU. In
addtition to its inefficience, the algorithm is also much harder to
understand.

Replace the logarithm formula with a simple loop.

package/gluon-status-page/files/lib/gluon/status-page/view/status-page.html

@@ -66,12 +66,17 @@
 
 	local function formatBits(bits)
 		local units = {[0]='', 'k', 'M', 'G'}
+		local unit = 0
 
-		local pow = math.floor(math.log(math.max(math.abs(bits), 1)) / math.log(1000))
-		local known_pow = math.min(pow, #units)
+		for i = 1, #units do
+			if math.abs(bits) < 1000 then
+				break
+			end
+			unit = i
+			bits = bits / 1000
+		end
 
-		local significand = bits/(1000^known_pow)
-		return string.format('%g %sbit', significand, units[known_pow])
+		return string.format('%g %sbit', bits, units[unit])
 	end
 
 	local function statistics(key, format)