regdb: Generalize the mW to dBm power conversion

Generalize the power conversion from mW to dBm
using log. This should fix the below compilation
error for country NO which adds a new power value
2000mW which is not handled earlier.

 CC [M]  net/wireless/wext-sme.o
 CC [M]  net/wireless/regdb.o
net/wireless/regdb.c:1130:1: error: Unknown undeclared here (not in
a function)
net/wireless/regdb.c:1130:9: error: expected } before power
make[2]: *** [net/wireless/regdb.o] Error 1
make[1]: *** [net/wireless] Error 2
make: *** [net] Error 2

Reported-By:  John Walker <john@x109.net>
Signed-off-by: Chaitanya T K <chaitanya.mgit@gmail.com>
Acked-by: John W. Linville <linville@tuxdriver.com>
[remove unneeded parentheses, fix rounding by using %.0f]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/genregdb.awk

@@ -68,17 +68,7 @@ function parse_reg_rule()
 	sub(/,/, "", units)
 	dfs_cac = $9
 	if (units == "mW") {
-		if (power == 100) {
-			power = 20
-		} else if (power == 200) {
-			power = 23
-		} else if (power == 500) {
-			power = 27
-		} else if (power == 1000) {
-			power = 30
-		} else {
-			print "Unknown power value in database!"
-		}
+		power = 10 * log(power)/log(10)
 	} else {
 		dfs_cac = $8
 	}
@@ -117,7 +107,7 @@ function parse_reg_rule()
 
 	}
 	flags = flags "0"
-	printf "\t\tREG_RULE_EXT(%d, %d, %d, %d, %d, %d, %s),\n", start, end, bw, gain, power, dfs_cac, flags
+	printf "\t\tREG_RULE_EXT(%d, %d, %d, %d, %.0f, %d, %s),\n", start, end, bw, gain, power, dfs_cac, flags
 	rules++
 }