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.

(cherry picked from commit f2e0f7e3)

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
+
+		for i = 1, #units do
+			if math.abs(bits) < 1000 then
+				break
+			end
+			unit = i
+			bits = bits / 1000
+		end
 
-		local pow = math.floor(math.log(math.max(math.abs(bits), 1)) / math.log(1000))
-		local known_pow = math.min(pow, #units)
-
-		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)