p54: fix powerpc gcc warnings

My commit "p54: parse output power table" introduced
the following compiler warnings for powerpc-allmodconfig

eeprom.c: In function 'p54_get_maxpower':
eeprom.c:291 warning: comparison of distinct pointer types lacks a cast
eeporm.c:292 warning: comparison of distinct pointer types lacks a cast
eeprom.c:293 warning: comparison of distinct pointer types lacks a cast
eeprom.c:294 warning: comparison of distinct pointer types lacks a cast

This patch fixes those by using max_t(u16
which forces a type cast.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/p54/eeprom.c

@@ -288,10 +288,14 @@ static int p54_get_maxpower(struct p54_common *priv, void *data)
 		for (j = 0; j < ARRAY_SIZE(pda->point); j++) {
 			struct pda_channel_output_limit_point_longbow *point =
 				&pda->point[j];
-			rawpower = max(rawpower, le16_to_cpu(point->val_qpsk));
-			rawpower = max(rawpower, le16_to_cpu(point->val_bpsk));
-			rawpower = max(rawpower, le16_to_cpu(point->val_16qam));
-			rawpower = max(rawpower, le16_to_cpu(point->val_64qam));
+			rawpower = max_t(u16,
+				rawpower, le16_to_cpu(point->val_qpsk));
+			rawpower = max_t(u16,
+				rawpower, le16_to_cpu(point->val_bpsk));
+			rawpower = max_t(u16,
+				rawpower, le16_to_cpu(point->val_16qam));
+			rawpower = max_t(u16,
+				rawpower, le16_to_cpu(point->val_64qam));
 		}
 		/* longbow seems to use 1/16 dBm units */
 		return rawpower / 16;